Check the length of the main shaft for the Pinto transmission and compare it to the A. A simple spacer might work. The A transmission is a bit weak for a Pinto engine. A T5 with a closed drive adapter might be a better choice. Let us know what you find. Good luck
Stock trans will work fine. You redrill the A bell housing to fit the pinto. I'll look for the notes I had when I did that in the 80's. I redid the trans later to use a 32 bell housing and a V8 style trans with later gears fo the synco's. We used a lightened A flywheel and a guy made an adaptor for the crankshaft to flywheel. Might check with some of the A clubs they may have someone who can remember it better.
I think the suggestion above re T-5 is worth considering. I am running one behind a 2.3 in my 30 mordoor and find it realy streetable as well as highway cruising.
I don't have an "A" transmission, yet. I build T-5s, so plenty of them around. I want a stock, otherwise appearing vehicle and knowing that the pedals come off the bellhousing, I was thinking of going that route. I will not be using juice brakes, So keeping the brake pedals and parts stock was an option for me. How would that work with a T5??