Value wise, the 70 Camaro wins hands down. The big bumper Firebirds look much better and are worth more than the same year Camaros but they are worth less than the earlier cars in general. You're not building for resale so don't consider it, at all. You'll lose money no matter what you build anyway.
I say build the TA though because it's in better condition now. It'll take less time and money to get it done. Besides, you don't see that many and it will look great.
Need inspiration? Go check out Skip's wide body thread. There's a 74 or 75 TA in there that's gorgeous if you haven't seen it yet.
Good luck! Post pictures of the build
