I have a GME TX3500 mounted over the dash. Its not waterproof, but has been there for years, in all weather and not got wet. Its coupled through a Sens SR10, to feed audio to and from the helmet via bluetooth. Helmet has a Sena 10S. I have wired the highbean flash button to act as the transmit button.
Antenna is a GME 3.5db I think, mounted down the back of the bike. I have tried a couple of hand held radios, but found the performance to be poor, as the squelch had to be turned up to kill background noise.
Dale should be able to supply most of these parts.