bore vs stroke

Not so krazy
I hope you meant- when discussing wear above- that the rod and crank throw were at 90 degrees not that the crank was 90 degrees on the degree wheel
When Rod is perpendicular to the crank is when you have the most leverage, torque, and side thrust this is also when piston speed is highest
But flow lags this point but you still want to have the induction flowing good
Note that the short rod engines get to this point many (a few but it matters) crank degrees earlier than long rod engines so the chevies have to start opening the intake earlier to get the flow curve right. One reason not to use a chevy camgrinder to spec your mopar cam. You can easily end up with more overlap and reversion

Some say the factory did not have enough capacity (or would have had to add shifts) to make more 383 B motors but the RB line had capacity to spare so they cranked out the small bore 383's
Good luck finding pistons :)
If you look at the production figures there were many times more B than RB