Mac90 and 930spx question

[Dirtball]

Working on finishing a couple of projects, namely a Norinco Mac 90 and a Mossberg 930 spx. First question is a rail question, anybody know if the full/long TROY rail will fit the Norinco? As for the 930 it's also a rail question, the only top receiver rail I've found is by GG&G for about $40 for a 6" rail. Anyone know if the 930 and the 500 share the same bolt pattern, or simply if a much cheaper 500 rail will fit?

 

[Dirtball]

I'm not 100% but I believe my front sling loop is in the wrong position for the rail, and I don't want to buy it to find out.

 

[churchmouse]

I have had several 930's and alway's bought parts specific for that gun