My override switch works fine, but I did do the yellow wire bypass that nacho speaks about prior so I never have to deal with it.

The original harness is pretty fragged, but I've plugged it all back in to get the engine through its run in. Then I'll deal with harness modifications, although the more I look at it, I think a complete aftermarket replacement with additional circuits may be the better route to go, even though the price tag is a bit steep.