retroblackrifles.com will be able to help you get all the details straightened out, and no matter what weird mix of parts you end up with, there is likely a rifle that was built that way at some point, and they have the label for it, so you can call it the right name...
One of these days I'll order an A1 or XM16E1 lower to make my 604 clone look proper, but then I'll have an extra A2 lower, and I have an A2 PG and stock laying around, so thats half a rifle, and I can't just have half a rifle laying around, so I'd need another upper and guts for that... A simple 150 dollar lower costs so much more than that.
Scott