If you Google Saiga conversions by Classic Arms you will find a few postings from Saiga12 forum. Looks like nothing bad and yes, you can continue to wrench on the rifle.
The pic on their website shows a US mag. Not sure if it is for 922r.
Doing your own conversion is not that difficult. Search in here and you will find a few threads about conversions.
This calculator helps with 922r fun.