After racking my brains all yesterday I came up with a simple solution based on the gear I have.
That Korg N364 is my top tier keyboard, on the bottom I use a Korg SG proX piano/controller. I assigned the SG the same MIDI channel as the N364, set the range so that the sound doesn't actually appear on the SG. The only thng on the SG I assigned to that common midi channel was ... the modulation wheel.
The SG's modulation wheel is just that ... a wheel, not a spring loaded joystick. So now the SG puts out the midi channels I always had it do prior to this, plus another one just so that its modulation wheel can control the leslie effect of the XV-3080 triggered by the top keyboard.
This may not make sense the way I explained it ... but it works! It came to me while I was watching TV.
Thanks for your help. In the future the cc pedal may be the way to go.