That seems to make sense of the conflicting info I was seeing on the big box parts website - some were 0.060 and the ACDelco "OE" parts were gapped at 0.040. So even GM's guys got it wrong out of the gate.

Just wanted to throw out another small update - I got an email from the place that made the first batch of circuit boards saying they're doing a 20% off sale until the end of December. So I'm simultaneously working on adding the ICP header and LED jumper circuits to the original 1.0 PCB design, and I also ordered a D580 and D581 coil and should have them in a few days. Once I'm sure the circuit will drive all the coils I have, I'm planning to order a fairly substantial quantity. If nothing else, I'll have a bunch of really cool bookmarks. :-)