4.5" and 33's here. Drives fine all the way up to 95mph (haven't gone faster than that). But I also replaced the upper and lower ball joints, all bushings, adjustable trackbars, drop pitman, new steering box, steering box brace, etc while we had it torn apart. Other than being higher up it drives pretty close to factory.
If you regear appropriately for the size tires you run, a 4.0 will have all the power it did before the lift/tire upgrade, which ain't much. Haha. Lol.
Do keep in mind, with larger tires, you won't be able to stop as fast (ZJ rotors are tiny). Also bigger tires act like huge gyros when going fast, making it handle progressively more sluggish the faster you go. If a deer runs out in front of you, you'd prolly be better off just to hit the damn thing. Lol.
I usually stay around 65-70mph for that reason. As others have said - just keep it slow and you'll be okay. These ain't sports cars, especially when lifted. :-)
Don't fear the regear.
Finished 4x2 --> 4x4 conversion.