reason 1: I swapped my old 2.9L drivetrain out for a 93 4.0L drivetrain with a 5 speed Mazda tranny. I got a rebuilt Mazda 5 speed. It was junk. I went through 3 of them before I got a good rebuild. The clutch setup with the internal slave cylinder is a joke

I went through 4 or 5 clutches in 2 years.
reason 2: Automatic is better for towing, in stop and go traffic, and considered by many superior for 4x4ing. (good and bad)
reason 3: I had a factory A4LD core with 160K miles on it. Maintained perfectly from day 1. I also had a friend of a friend who has rebuilt Ford auto's for like 40 years, he is capable of rebuilding an A4LD properly.
reason 4: With the help of my friends we have done this sort of thing before and were perfectly capable of ripping out the old and installing the new in a weekend.
So I gathered everything I would need, I had the A4LD BUILT, figured out the wiring harness, put together the cooling system and swapped out the transmission, the computer, the floor shifter, clutch pedals, etc etc etc.
Sucessfully completed the swap in a Sat, Sun, and Mon night. I had to re-locate an 02 sensor to clear my new shift linkage and the exhaust shop (also friend of a friend) welded on the truck with the key in the ON position. This fried the PCM and JET chip, but took me two weeks to diagnose correctly. I had ford replace the PCM and the exhaust shop covered the charges. So my 3 day swap turned into a 3 week dealership nighmare, but that is to be expected, you do enough drivetrain conversions and you will expect the unexpected
The 700R4 is a LITTLE more complicated then that. The A4LD is made to bolt into a BII behind a 4.0L. Ford made every part I used for the conversion for the most part
The 700R4, when built is far superior to the A4LD, mostly because it has aftermarket support.

When my A4LD dies (planning on 150K on this build hahaha

I will likely go with a C5/c4 automatic 3 speed with a different T case, because by then my truck will no longer be my daily driver and I wont need OD.....
good luck!
Oh I also could have gone with a World Class T5 manual transmission. I never thought I would own a car that was ot a clutch, but I gotta tell you with a lifted bronco, stop and go traffic, towing and at most times off road, the automatic is MUCH better.....