Look into the MWM 4.07 engine from south america if you want about the perfect power/weight/package. It will just make you angry that we don't get more diesel choices in the USA
The 4bt is still a LARGE HEAVY engine. It may be two cylinders shorter from to back than the 6bt, but its still a VERY tall engine top to bottom. Even the 4bt is about 750-800lbs ready to go.
I think the 4bt is more suited to repower a full size US pickup than a jeep. I'm not saying it can't be done, but gees that is 10lbs of something in a 5lb sack!
I love my 6bt in the dodge, some days I wished it just had the 4bt....
Boy oh boy do I wish we got diesel engine choices like the rest of the world!