Nobody has seemed to mess with any of that, mostly because the changes you talk about are street mods done by Eclipse/Stealth/3000GT etc type folks netting upper RPM gains. Lower RPM's with higher torque is what's needed when off-road generally. They seem to do all right stock with the gearing and everything they have. Trying to improve torque and horsepower, well, you are almost talking redesign of the engine. My .02ó.

89 SWB, V-6 5SPD, OME Shocks, 16.5X37's, 2"BL, SR axle, Gen2 brakes, Lincoln w/Superwinch