Yes on these thoughts and again GM went through what they called their 'Engine deproliferation program' before 1970 production, deleting as many similar applications as possible and cutting their suffix totals by maybe as much as half? .
I'll look for this info also know I've read something on the 402 bore reason before too...I'm thinking it was maybe 15-20 years back in one of Preve's columns in All Chevy mag? .
~ Pete