I had to go look and see if Rodney's casting came with the recess on the south end for the stock or not... I couldn't remember.  Most do I think, the Ballards I've built from scratch needed some creative setup and machining to cut the oval recess with tapered sides.  Here's a pic of one setup in process.
GT

The first picture GT supplied the side walls of the receiver have a bit more thickness where my receiver has about the same amount as the second picture and has the slight bevel to them.  Without going to the shop and looking I can't remember the threat tap I used for the tang. I know it is a little larger than the first picture. Closer to the second one. The sides of my receiver were ground parallel (I checked to be sure) so I used a 6 inch angle block and securely clamped it and turned a stub that slip fit the area of the tang threads. The other end I held in the mill. This got me close then I indicated for location and bored for the tap size. Did the front for the barrel threads the same way. Worked out good. Got to make some screws to hold the block together and hammer location. Then a through hole for the lever and a screw. Thinking of a 32-20 for a caliber. Can you use a .308 bore barrel for 32-20? If not what would you recommend? Thanks for the discussion and pictures.


JMH

In my experience, on original receivers the tang is prevented from rotation by the rear plug screw for the tang sight (or the screw for the tang sight base, if one is installed).  It goes through the receiver and impinges on the tang threads, acting like a set screw.

Of course a casting set doesn't necessarily need the holes if a scope is contemplated as a sighting system.  Even if a tang sight is mounted, any size base can be accommodated on the receiver casting, located at the builder's option.  But the stock bolt hole does act as a positive stop as well.