Hi I am putting in a new Lang's terminal block https://www.modeltford.com/item/5044E.aspx as mine looks like a 70's reproduction that is now too loose. There seems to be a sheet metal support covering where the 'other' mount screw hole goes? What should I do? Right now I can only put one of the mount screws in. See pictures of the firewall on either side. See the diagonal piece of sheet metal covering the terminal block holes on one side?
Clearly, the sheet metal is not stock. Someone may have repaired the firewall but I don't see why the patch was made like that. Cut the sheet metal out to expose the other mounting hole.
My inclination would be to drill through the sheet metal to create the second hold.
The sheet metal's not stock, so you're not defiling anything original.
Second approach would be to drill a big hole in the sheetmetal....a hole big enough for the screw and screwdriver, etc, to get at the general area from that side.
The second photo is small and dark. That diagonal appears to be the sheet metal of the cowl. I would not cut it.
If I remember correctly, your multiple-year touring has all sorts of non-standard improvisations. This may be one of them. Here's how the block is attached in my 1923 touring.
As you can see, there's a hole for access to the outboard mounting screw. You have my permission to make one.
I believe the reason they did that, is to be able to use the earlier wood firewall design terminal block, so the screws would not touch the metal firewall. Also note they haven't swaged over the hole yet for the wires, so this tells me these firewalls probably had the grommet.