THAT is why the pics come in so handy...that 4-speed ain't going to work without alot of messing around. It is an OD truck transmission, and the tailshaft is way too long. Notice the dual shifter bracket mounts. This is what I expected. To make that transmission fit...as mentioned before, you will need to swap the entire tailshaft housing, and mainshaft. You will also need an OD mainshaft as the OD gear is so much smaller, the mainshaft reflects that. Now you need to make a decision on that transmission. Other parts are connected to that decision. for example if you want a 4-speed, then the OD bellhousing will not work as the bearing retainer diameter is different.
THIS IS A GOOD START!
Just another quick point, those truck exhaust manifolds are not going to work...keep your 273 ones. They are a bolt on.
And do yourself a favor and just buy a pair of motormounts from Schumachers. The truck mounts will not position the motor correctly.