I do not have any experience with the 18F46K20 but two things that I think would make it a good one for this project are:
Internal Oscillator Block:
- 8 user selectable frequencies, from 31 kHz to
16 MHz
- Provides a complete range of clock speeds
from 31 kHz to 64 MHz when used with PLL
And
Enhanced CCP module: In PWM mode, this
module provides 1, 2 or 4 modulated outputs for
controlling half-bridge and full-bridge drivers.