What exactly are you looking to upgrade about the distributor? Other than fabricating a distributorless ignition system utilizing individual ignition coils and an engine management system to run them so you can ditch the distributor completely, I don't think there are many upgrade options. Upgrading to a performance coil, quality plugs and wires, and rebuilding your distributor with new vacuum advance, cap & rotor to make sure it's functioning properly should leave you with a pretty capable ignition system.

95 Montero SR
3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes