Easiest, chose a PIC with a USART... Bits and Parity can be set independantly for the Tx and the Rx and this solution has the best reliability and least software overhead for the job. Once initialised, all you need to do is pick up a byte from the Receive register when it arrives, and drop it into the Transmit register - not exactly a code intensive task! OK... so you need a little routine in the middle to strip-out Bit 8 and replace it with a parity bit, but hey, that's not rocket science either.