How many miles on it the one that crapped out ?

Did you install a resistor on the line up by the PCM < I'd have to dig out my old info to know which , to fool the PCM into think the line pressure is lower so the shift kit will actually work correctly ? I think your pressure should be higher than that , I have swapped VB's and seen over 150 psi, and higher, with the TV pushed full rearward.

A trans that is it's way south to begin with is only going to happen faster adding a shift kit , raising the line pressure should have firmed up the shifts, but you don't really have elevated line pressures by those readings ????

the front half of the trans is the same basically as a 727 , you need a couple of special tools for the OD section , you could just take the OD section to a trans shop and ask them to change out the OD clutches .