A standard servo, once modified to be a 'continuous rotation servo', is not longer able to perform as a standard servo. You cannot command it to go to a specific position and stop there like a standard unmodified servo. Once modified you really own a bi-directional geared motor driver capable of only variable speed rotation in either direction or to be commanded to stop turning.
So if you want position control, get a standard servo, if you want to rotate something in either direction and at variable speeds then use your present 'modified' one.
Many beginners buy 'continuous rotation servos' because they think they are getting a servo with some 'extra features' where in reality they are in fact not gaining a true servo at all, it's an ex-servo, the servo part is dead, not just pining for the fjords.