Try SERIN2/SEROUT2. Use two pins on each PIC. One pin to SEROUT2 and one to SERIN2. I suggest SERIN2/SEROUT2 because of the time out option.

When PIC #1 is ready for data it will send a signal to PIC #2 from PIN_X.
PIC #2 receives the signal for data on PIN_X.
PIC#2 will then send data one PIN_Y.
PIC#1 receives data on PIN_Y.