The SB304 is no FHSS but a T-FHSS receiver. S-FHSS and T-FHSS modes are both supported on the 4PM
Here some frame speeds, for sure running 1/12 you want the max speed so the R304 would be the best choice. The R203 is in the inside just an R204, even the 4th channel is working, it only needs a pinheader and an hole in the case.