1990 2.5L/Auto/2wd Engine Swap Question

[G23crawler]

Hey guys, Iv been trying to read up as much as possible but need some guidance. Built up a 90 2.5L with 6" lift and 35's. I bought everything to convert it to 4wd, right before I started the conversion the 2.5 started to produce a pretty bad rod knock. I'm afraid it won't last much longer. I race ultra4, so this is just my cheap trail rig when I don't want to use the race car. The MJ will get one tons and 37's or 40's this winter. But until then I need to do something about the motor so I can at least have fun with it for now. I have built multiple race car/buggies/rigs so I'm more than capable of throwing in an LS or 4.0L, just looking for some guidance on what will be the quickest easiest for now. Let me know your guys thoughts, thanks! 

LS swap and be done for good? (more expensive and time consuming) 

Rebuild the 2.5L, finish 4wd swap and drive it (is it even worth rebuilding a 2.5?)

Find a donor rig and swap in a 4.0L that already has 4wd (might be hard in my area to find the correct trim/year, in todays market they are worth more than they should be?) 

[Pete M]

I'd do a 4.0L 91-95 XJ with OBD1   you'll need to swap pretty much everything so it depends on how much project you want.

 

 

but then slapping in new crank bearings on a 2.5L isn't all that hard of a job.