1996 Subaru Impreza No gear engage after engine swap

I swapped motors in my 96 subaru imprezza (blown head gasket but the engine ran and tranny was smooth and shifted nicely). I re used the torque converter. All went well without issue except after starting the new motor, shifting the transmission does not engage a gear. I can move the shifter from park to rev. And the idled engine increases rpm approx 3000 rpm and then slows back to idle. Rev to neutral and neutral to drive is the same thing, a slight change in rpms, but no gear action.
During engine swap, when the torque converter separated from the tranny, approx 1 qt of fluid hit the floor. Upon re-assembly, I checked the transmission dipstick and found the level was high when cold. A second dipstick was found on the section between the Bell housing and the motor which indicated low level. I added approx 1 qt of fluid there and still no shift into gear. Fluid lines for radiator cooling were diconnected during then swap and they did drain out. They are reconnected and there are no leaks throughout the system.
Any suggestions? Do these systems vapor lock or get a bubble? Is there a way to resolve? Is there an electrical connection that could have come apart during the movement on the tranny during the swap that could do this?