As long as both the genset and motor are connected for 480 volts/3 phase, the genset will run a 277/480 motor just fine.
Keep in mind this however: A 100 kw genset is the equivalent to about 135 horsepower at the generator terminals. Now take into account motor efficiency (90% for a 3 phase NEMA design B motor), the best you can expect is about 122 HP before the genset becomes overloaded and everything slows down. OTOH a healthy 4-71 properly RPM matched to the saw arbor will deliver about 160 HP.
So it's unlikely you are gonna see as steady RPM at the saw with genset/motor combination as with the 4-71 setup you have now.