ZF 5 spd is probably the best out there, m05 ( mitsubusi) next up
I have both of those in 3 of my trucks, and have no complaints

 

Any modifications that need to be done to make them bolt up?

 

You will need the flywheel, a 11" clutch, hydro clutch and pedal set up.
You will also need the transmission crossmember, AND the driveshaft
There is no speedo cable hook up, so you will need an electronic speedo to run off the vss off the rear, or a halls effect adapter to make your mechanical speedo work

 

I am thinking I like the idea of rebuilding the original motor and using the transmission with the shift kit. I've never built a motor and have always wanted to.

 

The hydraulic clutch pedal is going to be the worst part to find. I'm working on a hand clutch control idea at the moment.

With the 82 body, only 83-86 clutch pedals will work. My idea would not require a pedal and would be fully adjustable for LOP and pressure required. I need to talk to some actuator makers for more detail on that.

 

If you have an engine and transmission already out, build those well and put them in.

And you could try a street demon 625 instead of the 600 Holley. About half the price new. The primary butterflies are smaller, and the secondary set is goggle-shaped for more kick.

 

FWIW, the AOD was also used behind the 351W in cars in the 80s so there are some beefier parts for them.