We found the problem! Isn't it a pisser when you THINK that you have all the right stuff and somehow it still doesn't work?
The B body drum knuckles he had were to blame. The inner wheel bearing to knuckle clearance was excessive. We checked a 73 Dart 10 inch drum knuckle and the bearing fit great. Who knows why the B knuckle was wrong. He tried another with similar results. With it all back together, the wierd problem was corrected. WAAAhhhhoooo!