If we are talking about a Saiga 12 you will only need 5 compliance parts to be legal.
On my conversion I replaced:
The FCG with one supplied by Dinzag Arms (3 compliance parts)
This is a Tapco single or double hook trigger (I used a double) in which the Hammer has been re-contoured to accommodate the larger bolt & carrier. Also one side has been shortened to accommodate the BHO lever.
The Gas Piston. On the Saiga 12 the piston in actually the puck that is located in the gas chamber. I got mine from Tromix. (1 compliance part)
The Pistol Grip. I chose one made by K-Var their part number AK-212B. The matte finish on their grip matches the hand guards and Russian buttstock perfectly. (1 compliance part)
Total of 5
To make everything work correctly you will have to gather a few more items...
If you plan on using the real Russian folder you will have to use the correct 5.5mm pin rear trunion and modify it by removing some material.
If you do not the larger carrier will run into it. I picked one up at rusmilitary.com
While you are there you will have to get the correct forward latch for the folder. It is very different from the one for a 74 and is not easy to get a hold of.
And then there's the trigger guard...
If you want a "factory" style guard you will have to modify a virgin Bulgy trigger guard and selector stop to look like this:
I have a tutorial on saiga-12.com that spells this process out.
The guys on saiga-12.com have a lot of good info on this subject. My build pictures and the trigger guard tutorial are on there as well.
Let me know if you need any help.
sKott