You will run into trouble switching to the higher RPM motor. The pitch of the fan blade was designed to move the required amount of air at the lower 825RPM speed. Spinning that same blade 250RPM faster (1075RPM) will nearly double the HP required. Hence, a 1/4HP 1075 will overload. You'd need at least a 1/2HP 1075. And that's IF the larger motor will physically fit in the motor support, AND have running clearance to the coil. Also, unit amps will go up - more airflow needs more electricy. Plus the run cap will have to be different. Add up all these costs and you're just better off finding a 825RPM motor.
GE was one of those manufacturers that made OEM motors for particular HVAC makers. 25 years later, you try to track down a specific motor number, and it's obsolete.
You don't need the specific GE # motor. Any 825RPM, 208-230V, 1/4HP motor should work. Just make sure the amps of the replacement motor are the same (or more) than the original. If there are no motor warehouses in your area, contact a local HVAC company. They usually try to sell you a service call, but will sell you a motor by itself (at a substantial markup) if you insist.
PM me if you have any more questions. Have the unit make, model, and serial number handy. I can research on my end and give you some motor options.