I was thinking about this last night. If I recall, you checked for power on the brown wire coming from the ignition switch under the dash when the key is in the start position, and you verified that it had power there, had power under the hood all the way to the coil.

The only thing that looked strange to me was that you said this wire only had 8.5 volts at the coil when cranking and that the battery (at that particular time) was reading 12 volts.

Looking at those numbers, it appeared to me that the battery was discharged as it should be around 12.4 fully charged and the voltage at the coil (when the engine is being cranked) should be close to 11 volts.

Or, if not discharged, there was a big voltage drop between the battery and the coil in the wiring which is not uncommon in these old bulkhead connectors or ignition switches....that is the reason we check the voltage along the path to see if we can isolate a spot where it suddenly changes...like between the brown wire under the dash and on the underhood side.

Finally, if the problem was not the battery, or the wiring, yet the voltage dropped so much, it left me wondering if the starter was on the way out and was pulling a tremendous amount of amps which would cause the battery to be unable to maintain the voltage and let it drop to the 8.5 volts that you read at the coil while cranking.

When you jumped from the battery plus straight to the coil, you eliminated the wiring potential problem. Assuming that the new battery was charged, that should have eliminated the battery being the problem.

Now, the unknown factor (to me) is the relationship of the brown wire to the ignition control module. On a car with a four pin ballast and a five wire control module, the brown wire directly feeds the coil but it does backfeed thru the ballast to the control module thru the green/red wire.

On the newer four wire modules, I have not checked to see which wire has been removed, but, I am wondering if those that are suggesting that the module may be the problem are correct.

At this point, I remember why I initially went to the GM HEI module and eliminated all this mess when I bought my car

If it is not the module, then I would try one more thing to see if the starter is the culprit. Disconnect the brown wire from coil +. Take your other battery, connect its plus to the coil plus and connect the battery negative to your engine for the ground...and try to start the car. If it starts then, it has shown the starter current problem to be the problem. If not, I guess we find another drawing board Cars, you gotta love 'em!