Dan,
You've seen these grips, they too have the W&K Roman Numerals on the inside. I also think the steerhead carving is very much in line with the other W&K M.O.P. carving I have seen.
Note the difference in this second set. They came off a nickel pre-15 that had not been engraved. IMHO the carving is "better" "more detailed" but it does not look like W&K M.O.P. carving.
Also, the insides of these steerheads have no Roman Numerals.
The gun (the pre-15) didn't ship to Texas...it went to Washington, D.C.
Bob