While you are at this, you might as well check for voltage drop out through the bulkhead into the engine bay. Identify switched ignition power out in the bay. This should feed your red trigger wire of your MSD, and your regulator "I" terminal.
ALSO some gauge circuits are what is known as a 'bridge circuit' and those type guages have a ground post which MUST have a good ground, such as to the steering column support behind the cluster.
All of those seem to be great places to look, thanks.
The two I quoted stand out for these reasons:
The switched ignition power that I run to the msd is the brown wire that went to the ballast resistor. I've been told that just that wire works, and I've also read that you need to use both wires that run to that side of the ballast. Well with just the brown wire we only got power during cranking. We had to use both wires together to get power during cranking and the "ON" position.
Also, checking the grounds on the back of the cluster sounds plausible since I replaced the auto column with a manual one also during this adventure, and had the cluster out.