I'm assuming the reason 50 to 60 years later that these mopar's are still running because of the exact machine work that was done at the factory. The individual attention every motor was given with that unyielding attention to detail...
and how many factory 340's had hemi grind cams installed with factory springs and churned 7000 rpm. and it lived. lol
same goes with the 383, did it and never hurt them. lol