I just finished a CJ tailgate swap on my TJ.
I made a 3/16" strap all the way across the flat spot on top of the tailgate to get toyota pickup latches to set out flush with my corner guards. I threaded the inner hole for the latch and used a cut off bolt into the strap. The outer hole is drilled through the strap and through the tailgate lip with a nut on back. Make a couple of ears for the latches to hook onto and it works pretty good. I just made 1/8" backing plates with nuts tacked onto them for the stock CJ hinges. I was able to fish those up into the factory cut out body holes under there.
FWIW if you decide to look into this I was able to find the latches on some low rider parts website for $1.16 each. So buying new is way cheaper than looking for used ones.