I'm presuming that you found this reference
here in section 17.1? It just uses a 360CPR encoder as an example.
There is no specific CPR specification for the Talon SRX--neither the talon nor the wpilib CANTalon class care about the counts per revolution of the encoder; all positions are expressed in terms of numbers of counts, so so long as you don't move your encoder so fast that the talon can't count, you should be fine (unless you are doing something particularly odd, this won't be an issue).
I can't find any other references to a 360 count per revolution encoder in the Talon SRX documentation available through vex, but if you are seeing something else, please reference it.