Hey Kip,
Good to see you back on the Stovebolt. There are not too many deco folks anymore.
I am just "fishing" here, so keep that in mind. Have you checked the drum diameter as in are they way too oversize? Could it be possible that the shoes are getting cocked and wont let go? Have you tried braking while in reverse to see what happens, does it unstick?
With the drum off and slowly depressing the brake pedal, are both pistons moving equally?
I think Brian's "flush" method is worth a try as it is relatively cheap and non-invasive. Who knows, you may get lucky. It may reveal some information if the flow rate on one bleeder side is different than the problem side.
Lastly, years ago I remember messing around with a friends S-10 that had one brake locking up as you are experiencing. We poked around everything only to find that the brake hose on that wheel was collapsing internally and not releasing hydraulic pressure. From the exterior, the hose looked perfectly fine.
Good luck,
Paul
