[Hank70SS]

Ok, you're referring to the frame as the chassis correct? Typically chassis means the body, sheet metal. No problem as long as I understand what you mean.

Nothing wrong with the way you have it grounded. No need for the braided wire to firewall unless you're getting ignition noise in the radio. Not sure the braided grounds will solve it but that was the original purpose for them. They were only installed at the factory if the car was equipped with a radio. No radio, no braided ground straps.

The yellow wire fed 12v to the coil while cranking. Open at the solenoid with the key in any other position except start. The other wire if it's original is a resistance wire, provided a reduced voltage, around 9v, to the coil while running. The insulation on that wire is cloth type material.
The reduced voltage helped the points last longer. The full 12v while cranking made it easier to start.

The IGN blade in the fuse block is the correct place for the HEI power unless you want to open the harness. Some guys replace the resistance wire in the forward harness with a regular 12g wire. That's a lot of work and the way you have it is fine, that's how mine is.

Yes the radio should be connected to ACC. Power only in run or ACC key position. You could also tap the original radio power feed but again nothing wrong with tapping the ACC tab in the fuse block.