Bear in mind that while a WG4 would be a preferred source of parts for your
WG4 that other Wizard models and other Mercury models could be source of
some shared parts. Kiekhaefer developed the 11 cu in twin for 1940 season at
request of Western Auto. The WG4 is the last Wizard in the series based upon
the original 11 cu in twin. The WF4 and WG4 have no counterpart in Mercury
lineup but prior Wizard and Mercury models were similar if not the same in
most respects. If you can't source part from a WG4 look at other models.
Don't feel boxed in to sourcing parts from an exact matching model where an
early Kiekhaefer is involved.