The 4500 red line for the 258 is pushing it, some will hit that, some wont. With the long stroke, it can be a lot to ask. The 4 cylinder should be at least 4500, its bore and stroke is closer to being square. I didnt have a tach when i had the 4 cyl, i just shifted when i felt the power drop off.
1986 CJ7, 4.2 w/4.0 head, TFI-HEI hybrid ignition, Clifford manifold w/Holley 390 w/cold air intake, OBA, 4.5" lift, Woody CV shaft and Tattons in front, 4.10 gears - lunchbox in front, Truetrac in the back, twin-sticked, blower upgrade for running topless, trying to keep it simple.
It's just a Jeep, and if you don't wheel it once in a while, it's not even that.