?? is, Does a performance Intake for a 258 fit on a 4.0 Head? Seems i read that using the later 4.0 Cyl. Head, is quite an improvement over the old 258 Head. Also thought they liked to fit a 258 Crankshaft in a 4.0 Block, to get a 4.5? Stroker. Problem with building a Stroker Engine, is it gets very expensive too fast. ( unless your talking a V8 Chevy, or some Fords). Going from a 4.0 or 4.2 (258). To a 4.5, or 4.6, isnt much of a gain for the money needed to get it done. My guess for a build, would be an overbored 258. With a late 4.0 Cyl. Head, Good Intake & Carb. Header. Im sure you can still get a lot of performance Flat Tappet Cams for a 258. Maybe somebody makes Roller Cam Kit? If they do, im sure the price is outa sight !
Building an AMC is like building a Mopar, twice the price. Look on sites & Forums for 4.0-4.2 jeep Engine Builds.