Found a Source for 10” rear drums with 1-3/4” shoe
I have a 10" drum with the 4.5" pattern from a B body. Invert the B body drum over the 4" pattern drum, center the middle hole. The 4.5" B body drum with a larger center hole, easy to have the center holes concentric, and have the new stud holes 1/2 way between the 4" holes. Hole pattern will look like this.