drive help
 

I have a gas boat and have nitro cars and trucks but I've never had an EP boat. I need help on choosing the drive. The boat is 18" cat to be powered by a stock 540 and 6-cells. I think I'll go with Octura hardware with an inline rudder (not racing). The strut is 3/16" and .130 flex cable. Is this the right size? Will it work?

I also need to know what size coupler I need to connect the motor to the shaft. If anyone has any pics of a similar boat it would be very helpful. Thanks. JD