Voltage to coil

Sounds normal. The dark blue going to the "big block" is the firewall connector going through the firewall. This is a source of trouble, as those contacts become burned and corroded

The brown wire is the "ignition bypass" coming from the ignition switch. This powers the coil directly when cranking the engine.

The "box" you refer to is probably the regulator. Should have two wires, a dark green to a screw terminal, and a dark blue to a "push on" terminal