72 318 Scamp. Low oil pressure 1 minute after startup.

IMHO..... I'd certainly pull a couple of rod and main bearings and inspect since it is out. It is an old engine.... nothing to lose but your time to put in the new pump and pickup and try to see how it will do, assuming it ran OK other than the pressure problem. Overall, the inside of the engine looks pretty clean.... looks like regular oil changes and no short runs or gas leaks in the carb to damage bores or build up scaly crud in the engine.

At least any bits inside the engine were nicely pulverized into tiny particles by the pump. But I gotta admit.... the 'no oil to the #8 rockers' has me wondering if some of the pulverized bits worked their way up there and settled in the back of that rocker shaft.... they would fall down right where the rocker oil holes are.

OP, did you get compression readings before you pulled it? I do not see them.