OP here...thanks all for the input.  A took a closer look and my converter to battery run is closer to 15' one way, with mfg installed 6g wire.  So a re-wire seems appropriate.  So I've decided to keep the WFCO and use as a converter only when on-grid.  It works fine in that capacity.
Then buying a Mean Well NPB-750 charger to use with the generator off-grid.  I can place about 3' from Batteries (which are 2 Weize 100ah).  I think a better solution than replacing the converter/charger with a better one (was leaning toward the PD 9200 series).  And I would still want to upgrade wiring if going the replacement route.  I have left over 2/0 wire from the battery install that I can use with the Mean Well.
Still open to suggestions if I'm still wandering around left field on this.