I would look at the shifter cable adjustment in the tranny, the early 727 with the cable shifters are real sensitive to that. I race several of them for a lot of years, I ended up taking the tranny pans off when adjusting the shifter cables, I would remove the C clip on the end of the male cable end that slides into the rooster comb arm and adjust the big wheel on the exterior cable until the end, pin, would slide, drop in with no forcing into the rooster comb arm hole in nuetral, 1st, 2nd and 3rd gear. If my memory serves me correct there is only one or two holes in the big wheel that will give you that adjustment, make sure and tighten the little retaining bolt into the case that holds the adjustment wheel still after each adjustment before checking the results of that adjustment I've seen the same symptons(SP?) on the later 727 with after market cable floor shifters, the pin has to drop into the hole in the tran shifter arm with no forcing on all the forward gears and neutral What is happening is the tranny valve body is not routing all the fluid to each gear properly, you can burn the tranny up with it not adjusted properly