Hope you're aware that it is currently illegal to install such a stock on a Saiga 12. However, if you're aware of that, I'm sure you're also aware that the wretched law banning such a modification will expire in less than three weeks. Any stamped AK stock and P-grip will fit. You will have to do the standard P-grip conversion with US compliance parts, which I've done three times on Saiga rifles. The shotgun should be just as easy. I can give advice if you are comfortable doing the conversion yourself and could use it. My first Saiga conversion seems to have just... happened. Got the compliance parts, figured might as well start, while I was waiting for more info... Ended up practically converting itself. I clocked myself on my latest conversion of a 223 Saiga, and it was under two hours.
Since you seem to be fond of Arsenal, you'll be happy to know that K-var is affiliated with them and offers the same US made furniture.
A forum community dedicated to hunters and enthusiasts. Come join the discussion about optics, trails, clubs, gunsmithing, styles, reviews, accessories, classifieds, and more. The friendliest gun forum on the Internet!