Rat Rods Rock. They are the true classic hot rods. Nothing is more of realistic example of the beginning of the hobby than Rat Rods.
Now about clones. This is a subject I have considered for my car. For me it all depends on the numbers. If your classic muscle car has all of the original components, keep it so. If it has a different engine than original, clone it. There is only two real ways to hold value in the muscle cars, all original and clones. For me I had the first thought on my baby to do a tube subframe, air ride, big brakes and a 528 hemi. But then I discovered that all numbers match so why destroy a piece of history? Adding performance is allowed, as long as you keep the original parts in a bag and all add-ons are bolt on.
But that is one of the beauties of the car hobby, it is yours let it reflect your feelings. If you consider value and collectablity, then retsore to stock. If you want a balls-out tire burner, build it. Just enjoy your baby.