Checking back in after seeing supraman's post. I last posted almost exactly 2 years ago after doing the 4.0 head swap and MPFI upgrade.
Still working fine and I haven't had to touch anything. Runs like a top. Love it, love it, love it and would never go back to the old setup!
A couple of notes after reading some of the later posts...
I bit the bullet and used the HESCO CPS kit and wiring harness. The CPS kit wasn't too bad but the harness was expensive. However.
It plugged right up and fit very well inside the engine compartment.
If you have the coin and don't want to spend untold hours modifying an OEM harness and/or fabbing up your own CPS mount, I recommend the HESCO pieces.
I did use the computer from a donor '94 Grand Cherokee and saved about $400. Other than the check engine light, my $27 CPU is fine.
(I even bought a spare in case of an EMP attack, but that's another story.)
Regarding head gaskets, bolts, etc. -
I used the 4.0 gasket and IIRC it had holes that matched up with the pins (dowels? not sure of the exact terminology) on the block so alignment wasn't too much of an issue.
Also, the block and tackle I rigged up allowed me to lower the head very gently and thus ensure the gasket was perfectly aligned.
Likewise the head bolts. The new head aligned on the pins, so the bolts only had to take tension, not side loads.
Anyhow, it's been two years of daily driving on/off road, interstate, etc. and not so much as a single issue (knock wood) so in my case all worked out well.
Finally, a question of my own: I used a standard throttle body from a Cherokee and it's fine. But can anyone say whether the 63mm Hesco unit brings anything worthwhile to the table?
"We are all of us in the gutter...
Some of us are looking at the stars."
~ Oscar Wilde via Chrissie Hynde