In case anyone is interested, the preamp tube task/layout for the Road King II (applies also to the Roadster and RKI) is as follows:
V1A First gain stage
V1B Second gain stage
V2A Third gain stage, Ch1 & 2
V2B Third gain stage, Ch3 & 4
V3A Fourth gain stage, CH3 & 4
V3B Tone stack driver...