New Question. This link shows #1 cyl fires is 90*. I thought TDC #1 was 0*. Truly odd fire. What am I missing?
The author started counting "0" at #2 TDC. It's unconventional but I believe the point was to illustrate that pistons on a common crank throw are 90 degrees apart. If you subtract 90 degrees from the numbers he used they'll match what I posted.

If two ecms were receiving this signal could the base initial spark advance be set to 0* and to 90* to create 2 ECMs firing 90* offset from each another?
Good question. I think you can get the ecms to offset timing using only one crank sensor although the number should be closer to 30 degrees. You wouldn't get nice, even injector pulses between the banks but with TBI that probably wouldn't matter. But I think you might have a problem starting the engine. How are you going to deliver correct spark to all six cylinders before the ecm takes over?

FYI this is very similar to a discussion about how to create 8 cylinder DIS from (two) four cylinder DIS modules each using its own crank sensor with 90 degrees between the two. The answer was to either use two ecms each running 1/2 of the injectors or to use an additional component to split the outgoing spark pulses to the correct DIS module. Without the means to design and build electronic circuits one is limited to using two ecm's.