How much information do you have on the car? Have the vin deciphered and then check to see if it is # matching. If it is a specialty car... R/T, TA, SE or Western edition I would go back to stock. Worth more that way. But if its just a lowly 318 or 225 six, then mod away. Go with what ever you wish and make it what you want it to be. You can make it a tribute R/T or go pro touring, pro-street or G-machine. Its up to you and you can go as far as you want or spend carefully and be conservative. There are more parts out for the Challenger than at any other time by the aftermarket. You can get almost any panel now and any suspension you want to run. Stock brakes to 4 wheel discs they have them. Look at E-Bay motors under Challenger and then watch the fun. Let us know how you decide to go and keep us uptodate on the resto. Good luck.