the rear end is the easy one - the front end, thats another story.
http://www.naxja.org/forum/showthread.php?t=23381&highlight=leaf
after about 3" the price goes up by about 400.
to do it right and get 4.5" you need to have adjustable UCA/LCA's and an adjustable track bar.
For the front on a budjet -
you want to go coil spacers and if your dead set on swaping the chevy 350 - then maybe you could get away with the F-150 coils and not have the harsh ride that i have heard of with them.
The track bar can be remidied by drilling a hole about 3/4" to the drivers side on the axle mount - but plan on carrying spare TRE's to replace the ones that go out from the crazy angle.
Arms i guess could be made - RE sells superflex joints and currie sells JJ's for like $35 a piece - and your local NAPA sells bushings for around 3-4 a piece.... however careful choice would have to be made as far as metal choice for sleves baded on size and strength as well as finding a bolt big enough to trust my suspention on.
Brake lines come off a stock YJ and will work for about 5" of lift (in my expierence) - New for 80.00 all 3 - or used for 10bucks from a guy in your local jeep club.
Coil spacers can be made, bought - i would not suest spacers larger than 2" - there isnt enough coil tower left after than and it would only take a little bit of flex to loose a coil...
the f-150 coils and the 2" spacers net 5" of lift (roughly) on a stock cherokee - so you might concider a 2" f-150 lift coil from a ford board or
www.pirate4x4.com to get the desired height. (being as the chevy 350 weighs more than the 4.0L)
spring rate calculators, and trail and error are your friends here...
hope this is helpful
-Ranger