Overheating rear end

Oh yes, sorry, I did skip over the backing plate. I swapped in the 9" ones when I swapped the shafts.
Stock 13" rims, 34 psi. No alignment. No power brakes, stock single pot MC.
No unusual noises, no rubbing of any parts inside the drums. Shafts and bearings slid easily into place when installed.
This problem did not exist with the old setup. I bled the brakes with a pressure bleeder and pedal feels good, but I suppose there's no guarantee that the bleeding is 100%
I wonder if the bearings are dried out? I didn't know these were sealed bearings, I had assumed they got some oil from the tube, but didn't really pay much attention.
Sounds like an easy next step would be to swap the drums out and see if the hotter side moves with the drum to narrow it down any.
Thanks for the tips guys, gives me more to check out, I'll keep at it