I know that you can do it but what engine fits and what has to be done to make it fit. Please help my engine died and i can get almost any 350 i want for my senior project and i have to do it this coming month!!!!

all 350's will fit but make sure it is a chevrolet due to the starter position.(passenger side).look up advance adaptors they will have everything you need for the conversion such as mounts.i would also try to get a turbo 350,turbo400 or best option a 700r4 88 and newer model.that is the best option due to a loewer first gear and overdrive. but if you do the 700r4 you will need the bypass kit so it will work without the computer.
but your absolut best option is to get a 4.2 from an older jeep anddo a 4.0 head coversion and stroke it. then you wont have to worry about adaptors,trans,and computer controls. and most likley it will be cheaper too.here are some sites on that.
4.0 head conversion
head conversion
stroker kits
hesco engines
stroking a 4.0
as you can see it will be faily cheap to do a stroker engine,as compaired to rebuilding a 350 and buying the require adaptors and such for a 350 conversion. and that would be a great project,in my opinion too many 350 conversions going around,kinda like mustangs and camarows they are everywhere lol

350 kit for a Cherokee? I've never heard of it, but maybe it's new. Josh... it's an XJ? Your profile says CJ-5.

it'll fit but good luck keeping it cool with the tiny radiator that will fit in there. a bronco 2 rad fits but it's small.

aluminum radiator, ditch the belt driven fan and get either 2 small fans or 1 big fan, and it might work.