Well, I replaced the starter solenoid and she still didn't start, and I've still been having a lot of issues with backfire through the carburetor. So, I started suspecting a valve issue...stuck valve most likely, but the question was why. I finally broke down and bought a compression tester from the local parts store, checked the compression, and guess what...no compression on cylinders 2, 4, and 6. No wonder the thing won't run and the backfire issue was so bad!
I began the task of diving into the problem. Removed the valve cover and instantly found three bent pushrods...all on the intake valves for those three cylinders. The valve springs were rusty and there was a ton of crud built up on all the parts. Worst looking engine I've ever seen on ths inside as far as oil sludge and gunk. I also found that the rear-most head bolt was missing an important part...its head! The head of the bolt was actually laying in amongst the gunk, and on further inspection looked like it likley had a minor defect at some point that ultimately caused it to fatigue completely through.
With all of the issues I've uncovered (bad oil, bent rods, stuck valves), I've decided to do a complete rebuild on the engine. The head is already at the machine shop and is getting the full treatment (cleaned, valve job, new springs), and I pulled the engine this past weekend and am wokringon the tear down.
Somebody warned me when I bought this Jeep, to be prepared to spend money on it. Here we go!!