Asking an embarrassing question here, because I didn't take a photo of this area of the car before removing parts for cleaning/refurbishing.
There are three bolts on the firewall up and to the right of the heater housing. What belongs there?
While we're at it, there's a bolt beneath the voltage regulator. Is this to hold a loop strap for wires to pass through?
Thanks in advance for your help.

 

Maybe a vacuum can? That's where mine was on my old 69 442 Convertible.

 

Nothing goes where the 3 bolts are. As for the bolt under the regulator, it is for one end of the braded ground strap.

 

The two on the left would have been for a vacuum canister for power trunk, power locks, or A/C.

 

Thanks, Nilsson, for the advice about the ground strap.
The car is non-a/c, has manual locks and no power trunk.
There appears to be a (painted over) faint outline of a 90-degree flange above and to the left of the top left bolt.
If nothing goes there, I can attach a photo of the '64 Green Bay Packer 88 instead. (Ha Ha)