I think that after the crash in the -8 you now need 1500 hours to get a job in a regional US airline by law. Even if you don't he would not have a chance with 650 hours and a hand full of twin time. The US is not like Europe where you can get an airline job with 250 hours if you pay for a rating and are very lucky. In the US you need to work your way up the ladder and instructing is a good way to do it.