The question here is what will bring the most money at resale on a restore. If the car is being redone to a close to stock condition, then original paint is the most desirable. It may not bring the quickest sale, but usually brings the most money. If, on the other hand, the car is getting body and powertrain mods, then doing a color swap to one of the more popular colors will be the best choice IF DONE PROPERLY. A good paint job is labor intensive, lots of teardown and prep, removal of the doors and glass, the motor and fenders, etc, etc, etc. I personally like bright metalic silver with hews of gold in it on early Z cars.