I think that the simple question of adding a few engine dress-up parts has sparked (no pun) the philosophical discussion about whether to go original or restomod, or somewhere inbetween.
In a perfect world, EVERY classic Mustang would be restored. But, these cars, although they are rare, are not as "hands off modifications" as you may think. You have to ask yourself: "am I making this 100% original for some future sale to a collector--or is this for concours car shows, or is it out of peer pressure/guilt to keep it as original?
Overall, I've told people to do whatever they want--as long as it can be brought back to original "in a day ot two". No welded fender flares, etc. "IF" someone wants to do that many mods, they should go get a fairly common '68 coupe and go for it (i.e. Green Hornet/Little Red clone, etc.).
I can appreciate the purist attitude. There is a lot to be said for seeing ANY classic car as it was originally, with all those details that bring back memories. The total look of original stickers, tags, belts, etc., is very cool to see at a show.
By no means do I set any standard for anyone's GT/CS. As for my car, I'm going to only modify it with CS-Shelby parts that were available only during mid-1968. But--it's all bolt on stuff. I have to remember that the 390's are more rare, and as time passes, the idea of restoration gets stronger.
Just my two bits:
Paul N.