1st , yes, there was a guy called George Stringer, "Internet Gunsmith" that did a conversion job but you still had to file the mags because of the width of the bottom of the bolt. really was a piece of crap. Don't know if he is still around, but no good anyway.
2nd , I own
3 Preban SKS 20inch with bayo factory conversions with std stocks
1 just like above but shortened to 16 inch barrel
2 Preban type 84 16 inch barrels with bayo and factory conversion and bolt hold open
3 post ban 16 inch barrel no bayo with 3 differend stocks
1 - Monte Carlo
1 - Thumbhole with wide forearm
1 - Thumbhole with narrow forearm
I consider the prebans to be the best SKS's ever built
the type 84's are very particular on mags, no so the others.