The cheapest I would buy is a
This omnibus f4 sd AIO
Omnibus f4 sd
seriously pro racing f3
these help any board, only penny's.
And if you can get a new rx
Ia6b or ia6c, FS RX2a, X6b
These all do ibus & ppm.
All signals go down 1 wire instead of 6 you have. Saves weight & messy wires.