Just curious but do you really need more? My stock one has had no problem with my two electric fans, bigger fuel pump (if that matters), and a farily decent strereo (700 watts).
Usually, most audio stores sell higher output alternators and I wish I could remember where my friend got his because it only cost him ~$100 for 120amps. One more thing, our hotair alternators use a bigger bearing than the higher output 86-87 alternators so I would stick with the original style and modify it.