Found a Source for 10” rear drums with 1-3/4” shoe
On a standard 14x5.5 rim, I can easily fit my finger in there. On a 14x4.5 wheel they also fit. However your rims or mags may be different. I measure the O.D. as exactly 11.5". I tried to get the Centric dimensional drawing, but I wasn't able to locate it.