Thank you Bill and John. That confirms what I'm seeing. The old rings seal much better I can only get the new rings to seal solidly when the oil passage has plenty of oil. Should I just leave the old rings?

Two more big questions. First, there is a three-eared bushing and race that go between the forwars tip of the tail shaft and the rear of the front shaft where they mate. Is it common to discard the race? My trans didn't have a race. The front drum is definitely a 78 - up unit.
Second, I've got the guts back in and I tried to re measure end play in the nose gear. Original end play was .047. I put the thinnest thrust washer in the kit between the pump and front drum and with the pump and gasket in and torqued down (175 in lb) I get .004 end play. I can turn the assembly with the nose gear by hand. And turn it in reverse and get the sprag to lock. It does not spin freely when I let go. I used the thinnest select thrust washer in the rebuild kit between the pump and front drum.

As for components that might change front to rear spacing, I've replaced front drum and bushing, pump bushing, all races in planetary gears, thrust washers between the drums and between the front drum and pump, and the bushing and race between the shafts. Clutches and steels too obviously.