I'm thinking about ditching the Stormwerkz FSM and manticore triangle and putting together the parts to convert it to a true side folder. In looking for a stock, which mm pin size should I be looking for? Also, I cannot perform this work myself, who is a reputable builder in Texas that could do the swap and refinish?

The Russians used to use a 4.5mm hinge, they now use a 5.5mm hinge. Bulgaria still uses the 4.5mm hinge.
The stock angles are slightly different, but it's not a big deal(imo anyway). Honestly, I'd just go with whatever you can get cheaper.
The cheapest one I know of is the triangle folder from AK-Builder. It's a clone of a Bulgarian stock and trunnion, made in Taiwan. I own both a real Bulgarian folder and the AK-Builder clone, can't tell the difference.

I believe JBI Armory is in Texas, they can definitely do it for you.

Tag

Yep. I had a Bulgarian 74 built by Jim and it was amazing. Sadly parted with it when needing money and regretted it ever since. I have delt with him a few times over the years and he has outstanding customer service, however he does tend to have a little bit of backlog. Maybe not now that he is doing it full time. Anyway, check him out online. You won't regret it.

Are you looking to SBR your Draco, or pin a muzzle device?

The Draco is already an sbr.

I'd buy the akbuilder side folder if I needed one now. If you have patience, and it appears you do since you have an SBR, then I'd go with a Russian 5.5, they seem to be easier to find these days.

 

K-var has the 4.5mm in stock.