72 Demon starts bogging sporadically once warm

Markzilla88 said
I just thought of this.... there’s a stock mechanical fuel pump still mounted on the block. It looks almost new. I’m half tempted to reroute the fuel line from the tank to bypass the electric pump and run it to the mechanical pump. Just to see if it’ll keep good pressure while running it

I would at least try the mechanical pump, what have you got to lose but a little time?
The other line from the sending unit is possibly a return from the engine compartment, there may have been a charcoal canister as part of the evap system, probably long removed by a previous owner.