What I found when rebuilding old cars is that they were not made to run on todays highways or have todays creature comforts. I try to lighten the cars as much as possible with aluminum where I can and sound deaden everything. I also improve the suspension up to todays standards and replace the front steering components with more modern parts. As for the engine, it has to have more power. More power is better, right? The transmission is rebuilt for power also. I never change the paint color from original unless I am going for a complete restoration. If you think your stock car is made for todays roads, find you a track somewhere and do 130 Mph and see if you do not kiss the ground when its over with.