You can use commonly available TWS434 and RWS434.
I suggest you the idea which I’ve once implemented successfully. (sorry I don’t have the code back up)
Suppose A and B are the bytes to be send. Take two more bytes X and Y. X represents the next data transmitted will be A and Y represent next data transmitted will be B. Now send in the following format and do the coding in the transmitter and receiver part accordingly.
Hope it helps.