Correct; direct bolt on. Newer head should bolt right up to old 87-90 4.0L block. 87-90 head could be used, but doesn't flow very well for performance upgrades. 91-06 4.0L HO head flows better for both fuel and coolant. Some like 93-95/96 heads for best flow. A stock 91-06 4.0L or even a mild cam is best unless you address other issues. 24lb Fuel inj from ford or A.M. will work nice for a poor mans 4.5-4.6 stroker. Any bigger on motor and cam may require Adj fuel reg, larger flow fuel pump, even larger injectors, and poss a ECM reprogram, or ??
My 97 ZJ 4.0L is getting 4.2 crank, 4.2L rods, 4.0L stock block (if possible otherwise .020 - .030 over if needed), a fresh valve job, ford 5.0L H.O. 24lb injectors, +99 4.0L equal length intake manifold, a modded airbox, and a performance muffler. I don't tow with that Jeep so I am gonna stay with the stock cam if possible. Should be a nice wake me up for the Jeep.