74 and newer is supposed to use the stronger cap screw rod.
1968-70 have the shallow dish pistons. all years of the 350 are supposed to have pretty much the same combustion chamber in the head so the only way to up compression is with piston dish or milling the block / head / intake.
the older castings MAY also flow slightly better.
there's not supposed to be much difference between the actual blocks.
The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
Government schooling is about "the perfect organization of the hive."
H.H. Goddard, Human Efficiency (1920)