Not getting 12 volts to coil

I don't know what you mean. The alternator is pretty much not involved during cranking. The important thing is the drop between the battery and starter, so this means the battery posts (not the cable clamps, the actual posts) as the source, and the engine block and the starter hot stud as the load. Several ways to go about this

For electronic ignition, about 10.5 is minimal, although some will fire "lower." Most older cars in good condition that don't have "too hot" an engine will start much lower voltage if equipped with breaker points, maybe down in some cases to "barely turns over."

Modern PM starters have helped immensely as they don't draw nearly as much current.

9V right at the coil when cranking is pretty low. The bypass (Ign2, usually brown) circuit should be providing that voltage. The bypass circuit is hot same as the yellow "start" wire but is a separate set of ignition switch contacts.

Possibilities are harness drop from battery, fuse link, through the bulkhead terminals, through the ignition switch and it's connector