Suzuki 2 Strokes

I'm restoring this machine and not sure what goes where. hoping you can help.
Main thing is, what is supposed to pass through the hole behind the bottom of the head stock; the one about an inch diameter and has a rubber grommet? Is it one of the wire bundles or a cable?

Also, where's the correct points to attach the heavy ground wire from engine to frame?

thanks for any help.

You're suppose to take pictures before any tear down to save yourself from any dilemma. Luck for you, I did. Here's the ground strap. Give me a minute and I'll add a few more pics of the head stock. These are from a 750, but the 550 nearly should be identical. If I remember correctly, the 550 ground is on the right side of the bike. Where the 750 is on the left.

Better idea of where the 550 one is. You can see it clearly under the side cover, near the oil pump cover. It attaches to the frame, engine mount.

Headstock, nearly identical on the 750. Except you have a down tube hole for the radiator.

Another headstock pic. Cables and main harness are routed along it's side, strapped with rubber.

A 550 headstock. To help.

Big thanks for the pics! They help a lot.
I did take lots of pics for the engine rebuild, but in terms of frame and wiring it was an abandoned restoration when I bought it.