Turns out, I missed the #7 spark plug when I was plugging in the plug wires. So the tapping/knocking noise I was hearing? Yeah, that was the plug wire trying to ignite the spark plug heat shield. Not the spark plug.
So. Got that fixed, and now she fires up and runs. Idles at 50+ psi of oil pressure cold. Still have to fix a heater hose that's hemorrhaging coolant, and then I can let her idle to temp. After that, I have to do the rear brake shoes and drums, plus all the springs and adjusters, then bleed the system completely front to back. Then an alignment, inspection, and registration. Then I can finally drive her again.
Yes I realize I'm an idiot for missing something so ridiculously simple. But I was in a rush trying to put her back together, and that was where I went wrong. I acknowledge that rushing was the cause of all of this drama. I welcome your (good natured) ridicule and ribbing.