got a good deal on a stamped thumbhole MAK with an underfolder receiver.
What are my options for a conventional buttstock?
thanks in advance, I promise I did a search first, I'm sure this question
has been asked a zillion times.

Pics?

I think these had a tang welded to the rear of the under folder receiver which has a flat backing. Therefore it won't take a standard fixed stock as the rear of the receiver is covered.

I've never converted one but am familiar with these as I keep an eye out for them. I was under the impression if you remove the rivet that is covering the under folder stock hole, a Chinese under folding stock will drop in. They pop up on gunbroker with the assembly. Some surplus sites have the stock frame itself.

Then cut off the tang that was welded on and refinish.

Again, I've never done one but this is what I have seen others do to convert them.

Just find a folder assy, & do the above. I remember seeing a few of these in 1989 just after the ban. A few actually came with the thumb hole butt stock with the folder assy folded. GARY

Receiver looks like this? knock the tab off and grind it smooth, then hit it with some Cold Blue, then slap on an underfolder stock assembly. Doneski.

Thanks for the help fellas.  I'll start looking for an under folder stock
and hardware

Yep I did an 84s sporter Norinco in 223, all I had to do was grind the head off of the rivet and slap the new stock on and cut the tang off and reblue, easy peasy.

I made this video a while back.
Hope it helps.