well I guess you have to ask yourself about YOUR car is as far as value..mine started life as a 340 ralley car(only have the vin to confirm this)...Im switching my 72 to a 70 ta clone ONLY because I didnt have a fender tag, no build sheet, no matching number motors or trans....Im kind of kicking myself for doing it and not just being more patient and just buying a 70...I have THOUSANDS into swapping it over (grill, fenders, rear tail light panel, rear tail lights, side marker lights and so on), I should have just rebuilt the motor in my car and drove the damn thing! three years into the project and Im still not close to getting it on the road!!
It depends on the project too. My '72 needed new fenders and quarters anyway, so, using 70/71 replacements isn't any different than using 72+ stuff, price is pretty close to the same. The grille was definitely more because I decided to go '71, but that's what I wanted and it still cost less than the difference between what I paid for my '72 and any '71 that was even marginally in my budget. And I like the '72 tail lights so I'm leaving them. So really I had to replace the majority of the parts needed for the clone anyway. My car has a fender tag and parts of the build sheet, but it was a 318 car to start off with and the original engine is long gone too. It won't be worth any less as a '71 clone that it would have been as a non-numbers '72 318 car.
And while I'm sure you built the car for yourself... If your ever have to sell it you know the buyer won't give you anywhere near what a 70 would sell for.....
So? Again, it's not likely to be worth any less than it would have been as a non-numbers, no documentation '72 rallye. Sure it's not going to get '70 T/A prices, but, it's a clone so it shouldn't. And had he tracked down a '70 to start off with the price would have been higher to buy it too. Making money on these cars is more about timing the market and getting a good deal on the front side, buy low sell high. Otherwise the cars that are worth more just cost more too. Yeah, you can sell it for more, but you're not any further ahead. Especially if you're trying to do some OE restoration, all those original reproduction and date coded parts just cost more, driving up the price on the restoration. I can buy everything I need from Summit and not care.
And really, would you be happy with a car that you have to keep all stock to have it be worth more or to keep from de-valuing it? I wouldn't. Yeah sure, having a real T/A would be cool, but, then I couldn't do what I wanted to it without "ruining" the car as the anal retentive purists say. I'd rather be able to modify the car as I see fit and drive the crap out of it than have to keep it all original and worry about running up the miles. It's a
car, you're supposed to
drive them. Otherwise it's just an investment, and that's boring as hell. You can't take it with you.