regulators set pressure, not the pumps.
something from a later model car/truck w/ v8, and should not be terribly difficult to find & use.
The LT1 pump is compact, it’s 5/16” outlet.
It’s stepped up to 3/8” by larger pickup tube.
Can be had for $16-$70 depending on brand.
Used in ton diff. GM cars & trucks.
Just one example, several others.
'88 GW (aka Babywag) and '90 GW (aka JUNKbucket) both fuel injected
1994 Caprice wagon