I find it really hard to be able to put an unknown on a hand. My calling an allin range from him is AQ+ and probably 77+, accepting that I am a coinflip but putting him allin here with anything but JJ+ or AK+ would not be optimal IMO. Given the situation I flat call his reraise at 100 NL and reevaluate the flop. If I have an overpair to the board or TPTK I have no problems putting him allin, but I prefer to have him be the one pushing than me.