Check out http://www.redstarmuseum.com/FAB10FAQ.html for more info. Pete in NH can set you up with nice PB stuff for it. If you have long arms, you may want an A2 stock verus a retractable stock.
I have a few A2's for around $50.
I have an Armalite M15A2 (.223) in which I am installing a new Rock River Arms trigger assembly, and I'll be selling the stock trigger set if you're interested - email me at firstname.lastname@example.org. Only fired 120 rounds.