I've currently got a fuel injected 4.2 in my Jeep. The shortblock was out of an 88 XJ and I took the head/intake from my 4.0 and put it all on the 4.2, I only had to do a few minor mods to make it work. Just fill the water jackets in the head to make it go on the 4.2 I also had to cut the front of my crank a lil bit to get the serpentine pulleys on it and made a lile bracket for my coil to bolt to and cover the mecch fuel pump hole. Other then that, run awesome and gobs of torque down low.
4.2 EFI - Pacesetter header - Flowmaster - 4.5" RE XD - RE Monotubes - 35" Trxus M/Ts - 4.10s - D30 Aussie - 8.8 Trac Lok - NV3550 - Centerforce Dual Friction - B&M Shifter - ARB Snorkel - Livewires - M8000 - Duralined interior - custon front bumper - custom brush cables - HiLift on the hood with lights
"Don't follow me, You won't make it!"