Could it be done? Sure. But why? The XJ manual trans will bolt to the D300 quite easily. Then you could keep your axles and avoid the fab work of converting the coil sprung XJ D30 to leafs and/or using the inferior NP231 tcase instead of the D300.
As for which 4L to use, the 95 and prior are easier to wire....and when it comes to electrical I like to KISS!
'84 CJ-17: 17" stretch, locked Toy axles, 5.5" lift, FI, AX15, D300 w/twin sticks, boatsides & junk.