Ok then;
This business could be one of two things; Either the VB is faulty or the F-clutch is. Pull the dipstick. If the oil is still bright-red, then I'm blaming the VB. If the oil is black, then the F-clutch.
Normally, the Forward clutch is engaged in all forward gears, and at no other time.
If the car creeps in Neutral, and the Manual valve is properly indexed, then the clutches in the forward drum are "piled up" meaning warped and the clutch is unable to physically de-couple. But since no other gear is selected in Neutral, the car still should not creep. And, as long as the Forward clutch is jammed up, the trans will still function properly in all three forward gears.
However;
when reverse is selected, the forward clutch is normally not engaged.
But if the forward clutch is piled up, the trans acts like you have simultaneously selected both Low and Reverse. This results in a locked trans and no reverse.
Getting back to the piled up Forward clutch. The trans should still have a normal neutral. Because you say that it creeps in a forward direction, this seems to indicate that at least one other clutch is dragging, or the one-way clutch is also piled up. But since the trans still has three forward gears, I'm leaning towards the one-way being OK.
Therefore, the most likely source of the creep is a too-tight L/R band.
But it really doesn't matter because the Piled-up F-clutch is reason enough to pull the trans and go thru it.
This is my opinion.