If you have enough valvespring then put a 1.6 rocker on the intake. Wallace shows you're only making 615 HP now so with a 'good' stage6 (340cfm) head you could make 650-675 still using a flat tappet and using respective parts/combo. Conversely, I don't see it being worth your while to mess with a cam that hasn't wiped the lobes and is running respectable given what I know/assume about the motor.