My SHO uses o rings which leak like a WWII U boat, while my 07 Fusion is still blowing cold without a recharge yet.
The Pantera has all Ford components and is not particularly susceptible to leaking freon, but it has a lot of joints to the system and the hoses running to the back are long and as a result the system takes more volume of freon to fill it.
It was designed to use R12 which for all intents and purposes isn't available any more. You can find people selling cans of it on ebay but it's simpler to switch it over to R34.
If you are going to do that, the factory built a larger core evaporator for that system.
There is a rotary compressor available. You can get them rebuilt for about $100 at a local parts store. They are a good idea since they run alot quieter and smoother then the big Ford York does.
You should change your receiver/drier too, but those are pretty much a universal unit. Probably originally Mustang units to start out.
The rule of thumb to go from r12 to r34 is to step up the sizes of the hoses one size to accommodate more volume in the r34 system, but the Pantera hoses are already oversized if you look at them. Probably to compensate for the lengths.
Presuming that all your electricals already work and if the heater/defroster does then they already do, you basically need to charge the system with freon.
It isn't complicated at all.
The main difference between the two refrigerants is that the r34 doesn't get as cold as the r12. The coldest you can get the r34 to blow is about 40f usually. I've gotten it down to about 37 degrees. That's cold enough to pucker your nippies for sure. C O L D. That's probably where the expression, "it's getting a little nippie!" comes from if you ask me?
The r12 on the other hand you can get to blow at freezing. You really don't need it.
40f is plenty cold. I don't know how you guys take it in the summer with the engine right up your back without it?
NY typically goes upper 90s with very high humidity in the summer. Seems like the humidity matches the temperature most of the time. No such thing as dry heat here unless you are talking about sticking your head in a pizza oven... but that can be arranged?
The a/c here blowing on you dries you out so that you can take your swimming goggles off. You wouldn't want to ruin your nice new leather seats soaking them in NY sweat would you?