Hello 74 P-NUT,
The problem with the 77 tranny is it is most likely a C-3 tranny.
They are JUNK!!! AND very expensive to rebuild so you do not want to go there.
If the 77 tranny is still in the car and you can check the door post for the I.D tag?
Look under the tranny code IF it is a W then the 77 tranny is a C-4.
IF you have the W then you can remove and just swap the bell house.
If the tranny is already out of the car?
If you post a photo of your 77 tranny SIDE VIEW I could tell you what you have.
The C-3 tranny has a different bolt pattern as it bolts to the back of the 2.3 head not the block.
As far as the T-5 goes I have a T-5 in my 72 pinto. from a 87 mustang I had my bell cut and welded to make the bolt pattern match my 2.0 engine.
TurboPinto72 made some cool brackets to mate his T-5 to the 2.0.
Maybe you could ask him for advice???
From Pintony