I had a CJ-5 ('73 304, soft top, 4.27s), and a CJ-6 ('75 258, 3.73s, hard top) as a daily driver for many years. I drove the CJ-6 on the CA 405 freeway from Santa Monica to Irvine for a year; I went at super-legal highway speeds, and I have the speeding tickets to prove it. I drove from LA to the Grand Canyopn and back many times, and to the desert and back regularly.
They are fine on the highway if not radically modified and if all the components are in good condition. If your Jeep is scary on the highway, either something is broken or worn out, or you need to rethink your tires/wheels/suspension choices.
1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D