I didn't think about the need to deal with the seam post welding to fit it to the action, which is I assume why it's the standard.
I have seen almost all of the videos from the big league smiths, and Heym actually uses a shoe-lump which is pretty much a Demi-block from what I understand and it is indeed soldered on. They even use it on their .600 ne doubles so it must be more than adequate for most if not all of the rimmed chamberings.