The late model (91-95) 20 gal plastic tanks will not fit in a CJ frame as mentioned above.
87-90 YJs with the four cylinder motor had throttle body injection. These are 15 gallon tanks and will fit in a CJ. The fuel fill is on the wrong side. I used it as is because I have a YJ tub. I don't know about flipping it around, might work. Would need to do something with the fill and vent lines. The 4cly tank/pump will run a Jeep 4.0 no problem, my used tank/pump has been running my swapped in 4.0 for 6 years. The fuel gauge sender will work with the CJ gauge but it will read backwards!
I've been told the pump will run a LSx motor, and will be testing that soon.
1983 CJ7, 4.0ho, NV3550, D300 4:1, Fr D44 Detroit, Rr D44 OX, 4.56, 35" SSTs on beadlocks
1967 CJ5, 231,T18,D18,4.88s,Warn OD, 11" drums, locked/locked
1979 K5, 454,TH400, NP205, D44, 14b, 35" BFGMTs