Thanks for the patience everyone... I am weighing several options to undo the previous owner's attempts to hack the fuel system back together.
Pictured is the Holley Sniper EFI Tank Module (12-308). I am seeing to metal lines in this photo but in the instructions to install there is only one line (Supply). Can any one confirm if it's one or two? Second, is the smaller line meant to be a vent line to a charcoal canister? Or is this a return line?
I ask because I am thinking of taking the factory sender out of the tank replacing it with this and plumbing a carburetor bypass return near the carb. This is the cheapest way I can think of doing this for now.
The factory mechanical fuel pump is still mounted to the block with the carb feed line disconnected as well as the tank feed line. The only line still on is the return line (for no reason at all). The previous owner simply took the feed line off the mechanical fuel pump and stuck an inline pump (screwed to the inner fender) with a pressure regulator and inline fuel filter to the carb.
I have no idea what the state of the tanks sender units are like other than when I switch tanks on the dash I can see fuel levels. Beyond that, I am completely in the dark.