Kelsey Hayes Pulling Problem

Over the winter I put my 70 Duster back on the road, bringing it back after a 10 year hiatus in the back of the shop. One of the bigger items on the check list was getting the brakes in order. To that end I installed a new master cylinder, pulled and cleaned the proportioning valve, replaced all soft and hard lines, new rear wheel cylinders and rebuilt the front calipers (original 4 piston KH). I did go with Dot5 fluid this time so hopefully a long term setup won't cause problems down the road.

Imagine my surprise when after the above I hit the brakes a bit on it's first test test drive and the right front locks up.

So, back to the shop bleed it again, no change. What I've found is if I brake in a smooth controlled manner, no prob. But in an emergency type stop, it pulls a LOT to the right. I've checked the rears, they're adjusted properly.

Next on my check list is to pull the right front caliper and see if I can spot a problem. I was aware of the rolling a o-ring problem and took I though great care to not do that.

Any thoughts? All help is appreciated.

Thanks, Ron