727 Trans and no forward gears.

Installed the Transgo 2 kit in my 727. The car ran fine for 20-30 miles of testing - nice solid shifts, etc. then started to loose forward gears. It appears to have full line psi in reverse as it locks up positively in R. However, there is very little to no forward movement when in D, 2, or 1.
The fluid level is fine with the engine running.
Has anyone run into this? Does anyone have any thoughts? Regardless of the installation of the Transgo kit, what would create a no go in forward gears?
I'm getting about 450 HP out of the New Yorker 440 rebuild but can't enjoy it. Kind of makes ya' sad.
Thanks.