Regearing takes a whole lot of stress off your drivetrain. Think of it as giving all the parts a bigger handle which which to apply force on the tires.
But aside from that, the 87-89.5 Peugeot trans (BA-10) is a notoriously weak transmission. I blew mine up running 30s on a 2wd. Be prepared that it could self destruct (slowly or quickly) and have a backup plan. The most common upgrade is to swap in an AX-15 manual trans from an '89.5-'99 4.0L XJ/MJ/YJ/TJ (the XJ/MJ are a mostly bolt-in proposition, the YJ and TJ require a bit more mods to work, any of them will require a matching 23 spline input t-case). Several people report that their Peugeot is still going strong, so if yours gives you no problems, keep it. Just be aware that many many more of us have replaced it. Keep the fluid level topped off and be gentle. :thumbsup: