At under 20k, you aren't gonna get much better than the Pacifica. Also, the guitar being old is not necessarily a bad thing because the quality control was good before these Japanese companies contracted Chinese and other eastern countries to manufacture their guitars.
You should try a pickup change (as one of them is not working at all). Also get a general cleaning and setup done on your guitar, which needs to be done once in a while. Low sustain could be due to wrong/poorly adjusted pickup height and bad quality cables.
About EMGs, don't expect them to improve your sustain drastically unless your current pickups are actually dying (sounds like it :D ) or badly setup. But they do have a nice slightly compressed tone. If you like single coil sounds, try out the EMG SA/SAV range.
There are plenty of other manufacturers too out there with excellent single coil pickups. Look out for DiMarzio and Seymour Duncan pickups too.
-- My current rig
Guitar: '98 MIJ Ibanez RG520 QS w EMG 81/60
Amp: Laney LC15R Tube, Fernandes 20W SS
Pedals: MI Audio Tube Zone Overdrive, Boss OD3, CS3, MT2, HM2, DS2, CE5, DD7, TU3, Beta Aivin DD2 Delay, Dunlop Crybaby 95Q, Stranger Vol Pedal, BBE SupaCharger
Others: Yamaha RBX 374 Bass, Yamaha MM-6 Synth, M-Audio Fast Track, Shure SM-57, Heet Sound E-Bow Plus
Wanted(pm if selling): EB VPJr/Boss FV500L,Ibanez w Original/Lo-Pro Edge