Anything's possible...
But not necessarily always efficient, practical, or probable.
AC alternators (casually referred to as 'Generators") are electromagnetic animals of reciprocating polarity, and contain polepieces and windings with capacitive and inductive reactance. This means they're characteristically somewhat resonant.
In 'English', this means that they LIKE to run at the pace for which they were designed. You can over, or underspeed one to get the frequency you want (since output frequency is armature speed and pole-quantity), but you may find that at some frequency OTHER than the design freq... it doesn't perform with as much chutzpah.
Disabling or modifying the AVR circuitry really doesn't give you anything different... the AVR MAY be a resonant-device, and you may run 'out of range' for it to be effective, but that's not what determines frequency or shaft-speed... it simply controls field intensity to keep output VOLTAGE within a certain range. While the AVR is doing it's thing, the machine's GOVERNOR is doing it's part... to try to maintain frequency spot-on. Unfortunately, altering the shaft speed DOES have an effect on voltage, and the AVR will "TRY" to correct it (just like the governor will TRY to correct engine speed).
There's quite a few variables involved... and the guys with slide-rules in pocket-protectors definately took a ride through the mill to get it right for the original intended application.
If you try to change it, don't be surprised if something gets kinda hot.