If you are not replacing the head unit is adding an amp, be sure the sensitivity is high. 87+. 92 + would be best.
I put in 6.5 4 way speakers in the sound pods on the rollbar. I also mounted 5.25" 4-way up front in place of the dash speakers. There is a mounting plate to convert to 5.25 made by a few places. You could easily make one out of wood. There are dimensions in some jeep forums.