https://willysjeepforum.kaiserwillys.com/showthread.php?2949-Cj2a-frame-vs-cj3a-frame
Type: Posts; User: 51 CJ3
https://willysjeepforum.kaiserwillys.com/showthread.php?2949-Cj2a-frame-vs-cj3a-frame
There was a thread a short while ago that mentioned an adapter to put the 2A engine in a 3A. Maybe that would help.