Brian,
I have owned and driven CJ's for nearly 20 years now. What is your intended use? They are great as a second pleasure vehicle, but can take a bit of getting used to as a daily driver.
A few good things, there fun, fairly easy to work on and gets parts for, and capable on and off road when set up right.
That being said they were made for over 40 years (1945-1986) and there is alot of variability in drivetrain strength etc.
The late mid to late 70's were great years for engine tranny packages. You could get a 76-79 CJ5 or 7 with a Borg-Warner T-18 truck four speed, 258 straight 6 ( AMC v-8 is an easy swap) and 354-4:11 axle gearing.
The 80's saw more production but the 258 started to get seriously hampered by smog equipment. Tranny got generally weaker, with the exception of the TF 999 auto and the T-176 four speed.
Alot of CJ's suffer from poor handeling due to worn suspension, steering components and lifts. These can be remidied, but make sure you test drive and assess one's condition before you take it on the highway.
The CJ-7 has slightly more room than the 5, but 5's are better for tight trails etc...........
Any other questions just ask...........
Here's a pic of my current CJ-5...with a pretty rare 'glass hardtop............one pheasent hunting this past winter, one from the summer. Jode