I put a YJ Wrangler dash & heater into a CJ-5 to get decent defrosters and better styling (a slow kick intermittent wiper motor & box went in when I changed to the Cherokee steering column); wasn't exactly easy, but not rocket science either (quite a bit of wire sorting, splicing and hole enlarging/egging), not a good first project, IMO.
Have put several custom dashes into rock buggies; pick a piece of aluminum plate cut to size, weld in supports and cut holes for gauges then wire... 'way easier.
thought about doing an early TJ dash into a CJ but, at the time, couldn't find a complete analog (early years of TJ) one in a color that I liked so I dropped the project... as I recall it looked do-able with some fabrication and trimming but it was too long ago to be certain now...
Enjoy!