290 is a bit much but not too, and it is sweet on the high end if the rest of the motor is set up to it. Recommend a distributor swap in your future. That might help some with drivability by improving low-end timing. 050 is $80 new.
With a stock set up motor the rev limit is more from the valve train rather than the crank. 912s got good cranks! Stronger pushrods and double springs on the valves improve the rev limit. Balancing is important too.
Walt and Ray are as good as they get, you are in good hands.
