"does anyone see this as a really dumb idea? "
not I...more like hot rodding creativity. It would be better IMHO if you could get the MSD to take out more on start up just because there would be fewer components involved, is this do-able? probably not since you went this route but it may be worth checking into since just about any micro-chip can be manipulated. And a question to appease my own curiosity...How does the MSD box know how long to hold the timing retarded? what tells it that the engine is running, tack input or something?