If its a 95 then its a YJ . Does it have square headlights ? They quit making the CJ7 in 1986 . Thats when they switched to the YJ,s
as for a 4.0 swap , you would need to change engine , tranny , and Transfercase and of course the computer. The tranny and transfercase have a different spline count , Therefore making them incompatible with the 4 bangers .
The differenials in your current set up should be 4:10 ( all 4 cyl. had 4:10's ) and would work great up to about a 35" tire.
although if you plan on romping on it alot and do the 4.0 swap , I would consider getting chrome molly's for the rear diff'. This is what i did in my 94 and never had a problem with the dana 35 and i was beating it off rocks.
If you end up going with the V8 then you will need to change all of the above plus the rear diff . ( a ford 8.8 or 9" would be good)
-------8.8 are almost a direct swap plus if you get the right years you will get disk brakes .
--------you can also get a dana 44 from a grand cherokee ( rare ) . the V8's with the tow package has these. They usually get scarffed up rather quickly.
sorry if I am giving To much Info but Aleast you will have some idea of what you will need
Oh and I moved this to the Wrangler section
2005 Jeep Grand Cherokee , 5.7 hemi,Blistein HD shocks and struts
, Eibach pro-kit , 20" SRT Reps, Nitto NT420s 275-55-20 tires, AFE stage 2 dry cold air kit Billet Technology catch can
, Imatation leather disco steering wheel cover
..... more to come