I sold mine a year ago, maybe more. It was just going to be too much trouble to make it 3-Gun useful. I don't remember who does the barrel hood mod, but it was cheap, like $75. It's on a Saiga forum online somewhere. I also couldn't find a source for chokes without doing a ton of research, so I gave up. I bet they're easier to find now. Someone is also undercutting a relief into the bolt so that mags are easy to seat when loading on a closed bolt. You can make one 3-Gun ready with the minimum mods for far less than an R&R gun, but it's still going to cost two times as much as the base gun, or more.
The bolt catch is on all models, but you have to pull the action open and then hold it while sliding the catch hook into position and then release it. It's not a big deal, but it isn't quick. The S12 is exactly like an AK except for the lack of pistol grip, the bolt catch, the piston puck, gas valve, and the enlarged components due to the larger cartridge.
Also, I was able to satisfactorily avoid the pistol grip mod by buying the skeleton stock. The mod would be better.