I think my 727 is fried. Now I'm at a crossroads...

all the more reason to suspect aeration
With the transmission installed, it is a lil difficult to pressure test the case. And since Chrysler put the stinking vent almost right above the input seal, that can make the diagnostic a lil tough too. But I must say, those front seals last several hundred thousand miles.
you can prove the servos and clutches with an air pressure test, but in your case I doubt you would learn anything more than you already know, with your description of the oil.
Honestly; Ima thinking aerated oil
or the pump is sucking air.
A deep pan may solve both problems.