...have you considered installing one of the 1970's MoPar "vapor-seporator" fuel filter cans
just before the flow-meter unit?
...I'll try to find a picture (below), but it basically was a regular fuel-filter assembly with three pipes: an inlet on bottom and two outlets: one for FUEL to carburetor and one for returning VAPORS to gas tank.
...here's a picture of a HASTINGS GF84 replacement unit:
