75 dart sport as daily driver?

The engine families use a bell housing design just for them. In other words, you need a small block bell housing for a small block, and a big block bell for a big block, a /6 bell for a /6.

The issue with manual trannys is you'll need one for a "A" body car. Short in length.
Then the 4spd's have 2 front bearing retainer sizes. They should mate without space.
I'm not sure about a 3spd retainer sizes.