The Merc RC box does not use the same cabling, so you are in for a significant expense if you want to convert to remote. Assuming you are electric start already, the 3B7Q843503 RC box alone costs $386. Then you need the bits to connect the cables at the motor, and the 2 morse cables to operate shift and throttle. If you have the helm (wheel ir stick-steer assembly for the steering cable), and if the old cable is the kind for tilt-tube mounting, you will also need the appropriate drag link and hook plate to connect the steering, as well as a splashwell or transom mount for the motor end of the steering cable, since the B2 did not have a tilt tube for the steering cable.
Keep in mind that the B2 is quite obsolete, and precious few carb bits are available for it, although the water pump kit is still available.
Unless you can find a used setup in a salvage yard, the conversion costs would far exceed the value of the motor.
It was a good motor in its day, but that day was 25 years ago.