Awesome! This may actually be less trouble in terms of sensor placement than digital hall sensors, since you don’t have to worry about the angular position of the sensors relative to the stator. Plus two sensors is two thirds the work soldering tiny wires and capacitors 
EDIT: Even better, it looks like 49e hall sensors don’t even need filtering capacitors.
There are ways to do fast atan2 approximation to reduce CPU load, which should be plenty accurate for this. Here’s a good one with max error 0.28 degrees: How to Find a Fast Floating-Point atan2 Approximation - Nic Taylor
And you could switch to 8-bit ADC when the motor gets above a certain speed so you can use higher ADC clock rate to reduce the reading time. Lower precision values, but higher accuracy since less time delay means the values you have are closer to the actual rotor position.