Probably a 345V8 engine. Maybe a 348 if it's been bored .020. ;-) My 345 (.030) is now a "350"
You can tell for sure by finding the engine ID boss on the passenger front side of the engine. Just behind/above the fuel pump, just under the side of the head. You'll probably need to scrap the grime away.
See the http://www.binderbulletin.org/faq
for a picture of the ID tag area.
Other candidates are a 304 or a 392V8.. or maybe an AMC 401.
Sounds like a T19 - wide ratio would be a 6.32:1 1st, 3:1 2nd. The close T19 was also offered, with a 4:1/2.4:1 1st/2nd gear. Depends on how big the "jump" is from 1-2.
Transfercase should be the NP205 divorce mounted.
Your motor is set back about 7 or 8" from the 69-73 models, uses a long (hard to find) fan shroud, and hard to find rear-dump exhaust manifolds. You should also have a ThermoQuad spread-bore 4bbl.
D44/D60 sounds right for a 200 (3/4T) with discs up front. 4.10s was common.
What makes you think it was an auto? 3 pedals?
sells replacement floor pans. I'm not sure about rockers. Also check the cowl for rust.
SSS can also sell you a copy of your lineset ticket with all of the factory installed parts. Open up the glovebox and fold it "all the way" down which should reveal some wiring behind the glovebox - and also you may find the lineset secured to the backside of the glovebox.
What else do you want to know?
-Tom Mandera, Helena MT
'72 Travelall 1110 - 1/2T 4x4 392 D44s 3.73s 33x12.50s - tow rig
'77 SII - 345V8/wideT19/D20/4.09/Locked/33s/soft-top - trail rig
'77 SII - 304C/727/4.89s/full-width/SOA/ race rig