Gary- Have you ever thought of looking in the 14 bolt direction? I'm planning on swapping a 14 bolt under my '54 3600 truck and I have also been plagued with a, "What to do with the brakes dilemna?" Anyhow, GM has a number of drums in varying depths that they used from 72-present. Most of the drums can be mounted inboard or outboard of the hub. The backing plates also have a deeper dish than the Eaton.
What I've also found is that the 14 bolt hubs will bolt directly up to the Eaton. You may be able to use a 14 bolt hub from a SRW truck and use the later 67-72 drum. The SRW hub will push your WMS out to about 65" though.
Anyhow, If you want some measurements from a 14 bolt (I have a 63" and 67" in the garage) or some measurements from my Bendix-brake HO52, I'll be happy to give you a hand.
BTW- I'll be picking up a disc-braked 14 bolt sometime this week, so there's more info to come on that.
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