In general, without the on-board computer systems on more vintage non-computered vehicles (engines, brakes, etc.), the real need for higher-power alternators is not really needed. The '76-'79 B-bodies (and probably C-bodies) with the electric heated rear windows had a factory 100amp alternator to support that ONE option. Prior to that, it was the police/taxi vehicles that had the higher output alternators (due to their radios and lights). Therefore, rather than 1990s, you might be better off using items from the middle '70s or so?
On the other hand, if the systems are in good condition, a modern 120amp alternator would really have no reason to be at full output unless it was due to a dead/failing battery situation where full output was needed for a short period of time. Like an ignition coil, an alternator usually puts out only what's needed, rather than full output all of the time.
Back in the 1990s, Fords seemed to be famous for smoking an alternator when it was paired with a dead battery. The voltage regulator put things to "max output" and the internals in teh alternator would smoke due to the spike in output. Lesson? Charge ANY new or dead battery FIRST, rather than relying on the alternator to do it. GM's didn't seem to be as prone to "smoking" the alternator, but it was always recommended to fully charge the battery whenever an alternator was replaced.
Just some thoughts and observations,
CBODY67
