I am pretty sure the LS2 is going in. I really hate carbs. I hate the 2bbl on my CJ7 and I don't like the edelbrock on this one. Its tuned poor, and driving a very limted amount today, you get fumes and such in the vehicle at low speeds/stopped with the top off.
I am thinking that with the top off, this is right now about 3600-3700 lbs (curb weight on the 4x4 is about 3900). So, if I go with the LS2, I shave about 140-ish lbs. And a 700R4/NP208 is lighter than SM465/NP205. So, even with adding 33" tires (on Aluminum rims), it should be about the same weight as stock, I think.
So, this motor came from a trailblazer ss, which weighs 4700lbs. With 4.56 gears and 33s, its the same gearing and transmission as the TBSS on 30" tires and stock 4.10 gears. Cammed TBSS's run deep into the 12s, so I think the performance level will be adequate for a street truck in the Jimmy, with several hundred pounds less, but a bit more wheel weight.