Welcome to the club! Any MJ is a nice one in my book. For clarification do you have an 86 Comanche? Let us know what engine you have in your MJ currently. A Toyota engine swap is pretty much a no go unless you have great fabrication skills, a complete understanding of efi systems and a shop at your disposal. 4wd swap is easy enough but still requires a front axle, transmission and transfer case as well as front driveshaft. There are several good engine swap candidates depending on what year mj you have and what is in it currently. If your thinking in terms of reliability, the Jeep 2.5 4cyl and the 4.0 I6 are both in the “legendary” reliability category if properly maintained.