No blueprints are available that I'm aware of. The pic below is what came in my Bulgarian kit. While this receiver stub isn't torch cut, it does have enough of the front of the receiver to measure from. I haven't seen any milled AK parts kits with the rear portion included. I know the milled receiver has an angle on the back, but I have no idea what degree it's cut. Maybe someone with a milled receiver would be kind enough to measure it (hint hint). You wouldn't necessarily need to make the receiver for the milled stock set. You could cut it for a standard stock set. You could leave the receiver sides a little thicker and do a little shaving on the stock to get it to fit into the smaller opening.
To be honest, I think it would be easier taking the measurements from a stamped receiver trunnion and incorporating it into a single unit with the receiver and stock tang.
The barrel hole and bolt lug recess would require a cutting on a lathe, or a special bit for a mill. The bolt lug recess is round and is larger than the barrel hole. To make this hole in a mill, you'd need to use a cutter with a shoulder behind the cutting surface like in the picture below (A T-slot cutter or woodruff key cutter) and a rotary table. You could also use a boring bar to make the larger recess for the bolt lugs once the barrel hole is cut. You would also need a T-slot cutter for the lower rails and notches for the bolt lugs.
You'll have to use the T-slot cutters to remove some of the metal inside the receiver. A standard bit would be fine for most of it, but you'll need to switch bits to undercut the rails.
I think it is extremely possible to mill a receiver by hand, it'll just take a LOT of time and careful work.