QUOTE:
Does a 90 degree V6 fire every 60 degrees of distributor rotation ? If it does couldn't you have just switched which coil was firing which plug to make up the 60 degrees of delay or am I missing something ? Maybe on a 3.1 60 degree V6 ?

Ok - All modern 4-stroke 6 cylinder engines fire once every 120 degrees of crank rotation. There are 3 sparks per crank rotation. This holds true for the 60° V6, the Buick 90° V6, and even the old Chevy inline 6.

Where the confusion starts with DIS ignition is what happens when the ignition switches over from "cranking" mode, to "ECM controlled" mode. During the time while the engine is turning with the starter (and for a few moments after it fires) the distributor, or DIS system is calculating its own "fixed" timing advance. This advance is based on the position of the crank trigger sensor, or the distributor pickup coil position.

After the engine starts, the ECM takes over, and at that point the timing numbers in the .BIN are in effect.

One might be tempted to reposition the crank trigger wheel or re-wire the coil pack so that the timing is no longer offset by 60°. This could allow you to use the stock .BIN settings. BUT during startup conditions, when the ignition module is controlling the timing in Bypass mode, the start-up timing would be WAY OFF and the engine would not ever start.

The ignition trigger wheel and DIS wiring needs to be set up so that the engine can start and run in bypass mode, and the ECM calibration adjusted for the reference offset of the ignition system.

Hope that makes sense! Got to leave it at that and get to work!
David