Thanks for the picture and links! I guess I should have been more speciffic - the gun in question is stamped (can't remember exact model right now), but on the ACE site I think the block furthest to the right will fit (will confirm before ordering with ACE). I'll drop in the folder buttstock welded by me in the open position, new FCG and furniture (as required by law), along with a US muzzle break (that's what he wants), and I think it'll be good to go. That solid folder lookalike thing might fit the bill, but I didn't see one for a stamped angle cut MAK90.
Now that I think that's ironed out, there is another topic brought up by the owner of this gun. He wants an odd recoil spring assembly. He said that in this setup it mounts just like the normal spring, but this one is in a metal tube and you can't see the spring. Looks like a slender shock absorber for your vehicle. He also said that it would be hungarian, or possibly bulgarian - but either way he's interested in having one. So I've got to ask - do you know where I can find one? It's a friend's gun - not a customer or something. I'm just helping him out.
Thanks.