My 2cents:
I think Kwizz was close.
In the entire history of Chevrolet, there was never a more "designed from scratch", full package, under one RPO number, race purpose vehicle than the '63 Impala Z-11. IF you look at everything that car had under ONE RPO #, strickly built for racing only, (with only 50 produced just to have NHRA sanction) there was never another Chevrolet produced with so many specific packaged features for one purpose.
Verne
