they're not actually Showa forks, you can't buy them for starters and they're nothing like the forks they made.
as for foes, I'm not sure but they don't look like foes curnutt XTD's

 Anything can be bought for the right price though i suspect you are right, but there are some pictures of a japanese rider with them? Or was it honda riders?
They look kind of like stratos s8 but the crowns are wrong. They look like the curnutts but crowns slightly wrong again.