Frank,
1.) Since you are planning to use this distributor with your 3 speed overdrive transmission, send your transmission wiring diagram to Hebels and ask if there is a problem with grounding the output of the converted 123 distributor for about 1 second. If this is not allowed, ask Hebels if they have any ideas how this can be accomplished. The reason for grounding the ignition is to quickly make the engine "stumble", to momentarily take the driving force away, to allow the transmission to mechanically drop out of overdrive.
2.) It would be nice if you could provide pictures of your converted distributor before and after installation.
