Reply to "Keep it stock or modify it?"

Great question ...

I think it all depends on the Marketplace you are targeting your car at.

My view is the following:

There are basically three marketplaces that you would be aiming at if you want to keep it for a period of time and have a mind to sell it:

1) If you want to sell the car as an original "show" car - then keep the car as stock as possible. This is the type of car that is primarily intended for a collector and is not meant to be driven regularly. It is meant to show the car as it was off the showroom floor with maybe a few miles on it. This type of car is meant for a top dollar but narrow market. An interested buyer here would have the money to spend for this type of car but there would not be a wide audience.
In this case, subtle non-obvious safety upgrades are good. (eg. Porterfield brake pads and SS brake lines are good BUT KEEP the STOCK Master Brake cylinder. Rebuild it and rebuild the original calipers.
The engine compartment should be entirely stock (upgrades here are would be visibly obvious). Upgrades to the A/C system are not worth the effort or cost as this would for an original "show car". Changes to electrics (wires, fuses motors etc.) - keep it original ("if it ain't broke don't fix it") - Not a safety item and not worth the cost or effort. Just make sure everything works and is bone stock or obviously so.
"L" front bumpers tended to get the undermetal rusty, with dried out and "wavey" rubber. Make sure the front bumper looks clean and not wavey. Good non-wavey bumpers are a challenge to source but are available. Alternatively, restore the original.
"L" cars did not have an chronic overheating probelm - the engine cooling sytem was largely sorted out - but change the hoses. If the radiator is shot - Get an original looking one. Forget a Fluidine.
Original wheels and tires (or tires that fit and look originalish - a toughy here).
The "L" exhaust header tended to crack at the webbing. Repair it. If the original exhaust is rusted out. Replace it with a new one. They are still available from the vendors.
Changing out all the old weatherstrip rubber for new looking rubber is a good idea. Polish up the bright metal work.
As far as the original paint goes ... My view is if it just has subtle chips and scratches (No rust in the bodywork) - DO NOT REPAINT. KEEP THE ORIGINAL PAINT. Spend the effort in a touching up the chips and scratches - give it a good professional paint detailing polish and wax. The cracks that appear in the "A" and "C" pilars are part of the originality. On the other hand. If there is rust in the bodywork, some dents etc. Then document (as suggested) the condition of the body and go for a repaint that is as close to the original colour as can be done. Since the car was originally painted in enamel ... Do not repaint in 2 stage colour/clear. Use a single colour coat system. Also, Do not change the colour. If it is yellow, keep it a yellow colour as close to the original as possible. Remember, the body was painted in one colour almost in its entirety. A colour change would be obvious.


2) If you want to enjoy and then sell the car as an "originalish" driver car. In my opinion, this is a type of car that superficially looks original and has subtle quality DeTomasoish upgrades to make it look and work better (upgrades typically sourced from the DeTomaso vendors). The car could be driven and shown. This type of car would appeal to the widest market. There is can be a wide range to an "originalish" car.
The car you are talking about looks to be an "L" car. L's had many of the "issues" sorted out and would be a good driver right out of the box.
Changing out all the old, cracked, torn weatherstrip rubber for new looking rubber is still a good idea. Polish up the bright metal work.
In addition to what I mentioned for 1), a Brake SYSTEM upgrade is good (Master, pads, lines, maybe even calipers). Working A/C is a good upgrade; compressor, hoses etc. (with original configuaration - ie, no front condensor). Maybe a quality smaller steering wheel (the original made the driving area feel tight for taller drivers - you don't want to cut these buyers out). Upgraded radiator (eg. Fluidine or Phoenix) and hoses. Wheels and tires that are Campys (eg. 8" wide rears to 10" wide rears) or look like Campys (quality aluminum campy clones 10x17 and 8x17). Once again, I would keep the engine bay bone stock. Stock motor, intake, air cleaner etc. - The stock motor worked and works well out of the box. All the engine bay requires is a clean-up. Keep the trunk as it was. Replace the cracked exhaust header with a newer vendor market header (not worth the welding) that is jet-hot coated. Replace any rusted exhaust with a new original unit.
I would keep the "L" bumper look. As in the case for 1) it all depends on how good the original front bumper is. An after market replacement is OK provided it looks "originalish". I would not go into the expense of filling all the holes and repainting for the Euro bumpers on an L car.
As far as the original paint goes ... My view is if the body has subtle chips and scratches (No rust in the bodywork) - DO NOT REPAINT. KEEP THE ORIGINAL PAINT. Spend the effort in a touching up the chips and scratches. The cracks that appear in the "A" and "C" pilars are part of the originality. On the other hand, for this type of "originalish" car: If there is rust in the outer bodywork or oxidized paint or excessive "waves" or dents etc.- then document (as suggested) the condition of the body and go for a repair/repaint. Colour in this case should be one that is appealing to the marketplace. White, Red, Blue and Black are good. (My car is original factory orange but I do not think that colour or DeTomaso lime-green are attractive to the larger non DeTomaso marketplace) Any non original colour repaint should hide the original colour paint as much as possible.

3) This is for a quality driver car that is primarily for your own use but possibly with the intention of selling down the road. This third group is for the marketplace that is DeTomaso Pantera knowledgable. You would probably get the same dollar as 2) but the marketplace would be among the DeTomaso aware. You may not get all the money back that you invested in the car.

This type of car purely and simply looks like a car that DeTomaso built as a Pantera, L, GTS, GT4, GT5 or GT5S. It is fully sorted out - and has no "buts". Everything works and works well. Hop in and drive. (David Berman's GT5 comes to mind, or Will Dimello's Grp 4)
For example: it would use quality parts such as "Pantera Electronics", upgraded shocks and springs, Upgraded "Willwood" brakes, upgraded engine components (intake, carburtation, etc.), upgraded interior (i.e. GT5 or GT5S leather interior in an early car.), upgraded wiring and electric motors etc.


Summing it all up: If you intend to sell, just like any presentation or sale - know your market and marketplace and target you product for that market.

Personally, I would go for the largest market and let the market bid for your car - which means my suggestion is 2).

HTH

BG