Check out my signature for information about my thread. I dropped a 4.3 in my 1992 YJ. It is "frame up" restoration but it has a lot of information that can help you. I posted a lot of photos and put a lot of information just so people like you can see what it is going to take and make an informed decision. It is missing in a lot of threads with conversions.
Check out "YJ V6 Conversion" if you want to see a frame up restoration of my 1992 YJ.
Check out "WWII Jeep Photos AND Restoration of..." if you want to see the original JEEP in action...