There isn't a lot to go wrong on a S-12 conversion.
There are no magwell mod and there is no need for a bullet guide.
Those are the things that seem to get screwed up on 7.62 and 223 builds.
Bunch of half-ass conversions where they don't bother with the bullet guide.
But that's not an issue on the S-12 or 308.
The only things you need to do on a conversion are:
-Remove the stock trigger and trigger guard.
-Cut a square hole for the pistol grip nut
-Install a trigger guard and selector stop
-Install a new trigger group
If you want a first class conversion you would want to fill the extra holes left over from the extra trigger pins and a couple on the bottom of the receiver.
I used a standard AK trigger guard (trimmed down) and fabbed a selector stop from a chunk of the factory trigger guard.