Things to look for: if there are bolts through the kick-plate (under the CP area) and it has no speaker slots to the right of the coin door it's not Namco....AFAIK.
I think there are also bolts on the sides of these cabs, Namco Japan machines are absolutely without any of those on the sides.
Weren't these even ID-ed as French clone cabs ? Karetco or something ?