In the mean time, check to see if there are any GOOD trans shops in your area that "know" Chrysler TorqueFlite 727s. How much for a general rebuild using OEM-spec bands/clutches, etc., with a converter and cooler (w/lines) flush.
I suspect that if there's fluid in the trans and "nothing happens", even if the filter is restricted with friction material, a new filter might then indicate a worn front pump, etc. The band adjustments might be a diagnostic situation, but I wouldn't count on it fixing anything. Just my gut suspicion. And I might be wrong, too! Hoping that I am, but do the checks just in case you need a reman unit or rebuild your existing trans.
Just a normal OEM-spec rebuild is all you need. Letting somebody do "some little tricks" of their own can cause other operational issues, by observation. Maybe some upgraded friction plates or band, but nothing else. Get it running well and THEN do the shift kit stuff, if desired. B&M, TCI, and others have overhaul kits and such. Maybe even something in Mopar Perf?
Keep us posted,
CBODY67