Fuel tank selector valve

[dlowry]

I posted this several days ago, but perhaps it went to the wrong area.
I have a 1979 chevy K10 with a bad fuel tank selector valve. As everyone knows, including me, now, the 6 port single wire valve is very rare, i haven't found one, the replacement requires adding wires from the dash. Has anyone ever replaced it with a 3 port single wire valve, which are all over, online and cheap. it would require blocking the return fuel lines from the fuel pump and both tanks, no big problem. Other than reducing pressure on the needle and seat in the carb, i don't know the function of return lines, possibly emissions, i don't know.
Any help.