Alternatively there is yet another project (eventually approaching full rewrite) http://www.moddb.com/mods/ja2-stracciatella
aimed primary at cross-system compatibility. I haven't used it myself, but as advertised, it tries to be very respectful to the original, although in games like JA2 the line between bugs and questionable design decisions may go very blurred at times, so no guarantees your favourite quirk of the game haven't changed behaviour in that version.
It also is independent from and incompatible by design with 1.13 what is considered too intrusive and much too big blob of strange features by its developers.
Both projects are still actively developed so don't settle for years old "stable" versions but search for the latest in relevant places, Bear's Pit
for 1.13 and latest Stracciatella
moved to Github for development.