Yes you should be able to swap to a 231 but the shifter linkage will need to be sorted out. There is cable shifters out there that should correct this. The 300 and 231 have the same bolt pattern which is why you swap them out, but you can also clock a 300 (rotate 180 degree) and run that as a driver drop case. The shifter will have to be corrected and you will have to plug the vent and add another vent in another location. There are threads on this around if you look hard enough. Good luck.
Two jeeps, neither like to work.