Rear drums locking easy after Power Disc conversion

[hank scorpio]

Just finished up doing the power disc conversion on my c10 from the original manual drums. Brakes before stopped ok under 40mph but were pretty terrifying from anything above that. No locking issues.

After the swap the rears would lock up under any sudden application of pressure. Went round robin on bleeding, checking everything. Improved after the fronts bed in some but only a little. Ended up checking the rears and they were adjusted way too tight. Lug nuts were noticeably hot after a short trip.

Backed the adjuster (and hand brake off) and it's better. It doesn't lock if you increase the pressure gradually (normal braking) but under a sudden application it still locks the rears easily.

When I had the rear drums off the rear pads were looking a little thin so it's probably time to build them anyways. There was no fluid or grease inside the drums. Truck has 240k and while always maintained well, it probably only put 500 miles in the last five years on before I ended up with it.

For those who have done the power conversion, is the locking normal? Seems to me this is locking in an unsafe manner. The proportioning valve is marked PV2 (which should be correct) but don't know which end I'm chasing an issue here on.