200,000 vs 150,000? Hell the newest CJ-5 will still be 26 years old. The oldest could be 55 years old. A CJ-7 could be between 23 and 33 years old.
if you're looking to buy a cheap Jeep, then I'd look elsewhere. Your cheap jeep will turn into a great big money pit. Especially, if you can't do your own work on it. You can't trust any of the original stuff to be 100% and you can't trust that someone didn't hack it up. The engine is the least of your worries although, 150K and 200K is a lot of miles for those old engine. Who known how they were kept up or not. If I was buying an old CJ, I'd expect to have to replace the engine at the very least. Probably all of the wiring as well. Springs are probably shot. Flush all of the fluids, repack all of the bearings, replace the brakes, etc... That is, unless we're looking at a Jeep that was well taken care of.
If you want a Jeep that you can drive then I'd look at a YJ or a TJ.