MPC might be overkill for your project. These things are quite difficult to get up and running. MCF (ColdFire) might be closer, maybe a Flexis part. All of the MCF51 parts have SCI, SPI and I2C.
Do you really need a USART (the "S" means "Synchronous") or do you just need a UART? The SCI in the Flexis parts should do what you want.
For what you're making that may be overkill. You might get by with a PIC.
Tom