No spark from coil

Okay, you are not getting spark correct? Here is a test, take a test light and connect it to a ground, now probe the positive side of the coil with the key on. It should light up. Now that you know you have a good ground, disconnect the negative wire (gray) from the coil. Touch the test light to the ground on the coil and watch for spark at one of the plugs when you remove it. That will tell you if the coil works. From there you will need to check the gray wire at the SBEC (control board) pin 19. Try tapping that pin with the grounded test light it should spark like it does at the coil. If it tests okay but still no spark check the auto shutdown relay to be sure it works. If those all check out, then the SBEC is likely faulty.

It sounds more like you have a wiring issue where some parts are getting power. It could be a ground issue or power or more likely corrosion in the various connectors because it has been setting that long. As much of a mess that it is I would probably start by unplugging each connection I could find, spraying in some contact cleaner and then plugging it in out a few times. That should remove any corrosion.
From there take a meter and check the power and ground connections at the SBEC. There are battery voltage, 5 volt and 8 volt feeds as shown in the pinout.
From those it will give you an idea of what you have. I would suspect corrosion may also have gotten into the SBEC and caused issues there. Also, the tech info on these is somewhat sparce, so I would look to see if you can find a real OEM service book on it that shows all of the wiring. Attached is what the info we have shows for the power train and it's missing a few things but it should help some.