FWIW, You can convert the 92 magazine to work in a 92FS, and It looks like you can do the reverse as well. The size and shape of the magazine are the same. I have been using a 92 magazine in my pre-ban 92FS for years as an extra. All it takes is a little work. As long as the pre-94 mag functions in the original firearm it was designed for, it is legal to use in any other type of firearm, pre or post that accepts it, at least from a Federal law/ATF standpoint. Simply cut a notch for the mag release with a Dremel. Use the 92 magazine for measurements and shape of the hole. (I'm not sure if this will work with a 10 round mag as all of mine are hi-caps.)
This looks like a deal to me!