Fresh 727 Street Strip Trans S.B. Wont Drive

Spent the last ten days sorting this new trans out , Basically Broke the Sprag in My last Trans .Got Another Casing rebuilt everything bolt in sprag etc, Clutches plates all new , put manual valve body in etc, had to use my original pump housing as my edge convertor would not fit the other pump that came with the casing, counted splines etc , problem is new trans wont drive fwd when on the ground, but will drive with back wheels off the ground, It wants to go fwd but then as I press the gas pedal lightly to get it to move It whines:mumum::mumum: