Multi-Rotary update.
Neither 2600 or Takeman are making any of the kits at the moment so I'm going to have to make my own. Looks pretty simple, instead of trying to get all fancy with male 13 pin 2.5mm headers on the multi-rotary board I'm just going to use standard 2.54mm pitch solderable protoboard and solder the ends of the harnesses I am making directly in, each harness pin separated by by a diode except for pin 1 on each harness that will be bridged.
I can build a single board that can house two sticks for 3 games for about $14, just a matter of soldering 48 diodes, 4 bridges and 78 wires.... who says I don't know how to party.