Pre-war (up to 1942) 1928 Cadillac 341A fuel gauge adaptation

[crankncog]

I am trying to adapt a modern fuel level sending unit onto a 1928 Cadillac 341A. The original sending unit has wiring different from a modern unit however. Attached is a photo of the diagram. Is there any way to modify the wiring to accept a modern sending unit with only a signal and ground wire?

[bcroe]

Later fuel gauges (like my 62) only need one wire
back to the tank unit, which returns through body
ground.  You could use one of the original wires
with a matching gauge, use the other wire for
ground return if the 28 does not have a good metal
path.  The newer gauge will have 3 connections, to
gauge power, ground, and the run to the tank unit.
Bruce Roe

[V63]

Maybe the least invasive way would be to use a sender w/float assembly and dash gauge from a more modern 6v car, mount the gauge part under the dash?

I just purchased an interesting gauge unit from HOLLY it uses an "eye" to read the level of the fuel in the tank. Nothing is submerged in the fuel in the tank. It is only 12v source however.