And a warm welcome to the PI forum. Perhaps one of the best places for Pantera talk and information.
My thoughts (others may differ and it's all Good!!
)1. Going to Chrome, original moldings are stainless steel (others, correct me if I am wrong) This may be perhaps the hardest of your requests as the trim can be difficult to locate if you intend to replace it with polished stainless. You may be able to soda blast the black anodizing and polish the trim or send it out to have it redone. I am doing that with a 66 vette and 69 cuda. Took me almost 2 years to locate drivers drip rail trim for one of my pantera restorations. When I saw the second one on e-bay, I bought it just for spite.
2. Removing the delta wing is easy, 4 bolts and its off. I have seen some people cover the holes with molded plastic plugs. Same type used in the door arm rest. Actually looked okay. If you want to fill it, really only way is to cut small metal plug and weld then grind smooth. Repaint deck lid to match. Nice option may be to paint semi gloss black like a GTS. What color is the car?
3. I as well as many others have done the same with the L bumpers. I suspect they will be a rare item one day. You will have large holes in the rear valance where the rear bumper shocks were. Again plugs or weld and paint. Front will also have holes but you have some options. Ameri-sport offers a kind of split bumper that usese the same mounting holes and looks cool. If you use 71-72 bumpers they won't fit right without doing some cutting and fabrication, there is a kind of indentation on each side. Best option, Euro bumpers, there is a pair on E-bay right now from Panteragirl. I got a set for my next pantera project. Most of these options will require painting but can easily be hidden when new bumpers are installed.
Lastly, Slow...are you kidding me? These cars look like they are doing a hundred when standing still. Contridiction of terms, no such thing as a slow pantera. Okay, truth is unless you are racing it on a track somewhere, where are you really going to use all the power that a few extra ponies would offer? I have had a stock 74 and have a 500hp car now, if you are just going to take it to shows and have fun with it, stock or maybe a small cam or headers is plenty. Just my .02 cents