Shave part of a firewall (ebody)

Looking for some bodywork advice for to the best way to shave part of a firewall (for this e body). I will be installing a vintage air system so i do not need all the holes for the old plumbing.

Would i be best off welding a "patch" sheet over the area marked in red and using filler to blend it in?
Or put the patch on the inside of the firewall and weld the holes flush to it then filler holes.
Or cut out and weld flush pieces for each hole individually?

thanks

Depends on how well you can weld. A flush plug metal finished will be the nicest. Laying the ptach behind is easier. Cutting the entire piece out is unnecesary.
Doug

Depends on how well you can weld. A flush plug metal finished will be the nicest. Laying the patch behind is easier. Cutting the entire piece out is unnecesary.
Doug

If you are wanting to use accurate fitting laser cut plugs to fill these holes, we have made up kits for the B and E-Body applications. The original intent was for those people wanting to use an AC firewall in a non AC application. But the restomod guys have been buying these kits to slick the firewalls up. If you need more information, drop me a message.

I'm smoothing a firewall on a b-body. You can see the large area outlined in the photo. The point is to get rid of factory stamping wrinkles, unnecessary holes, etc and end up with a nice smooth surface. I have both mig and tig but I came to the conclusion that one large panel would be easier than a bunch of small plugs, etc..

The 18ga panel will be screwed in behind then the two cut out together so the new panel is a close fit. I'll probably mig it. The large dimple for the heater motor will be cut out of the original and put into the new panel.

This right here is one of the reasons this forum is awesome. I never would have guessed pre-cut firewall fillers existed. How do i order?

The ebody firewall has several bends that would making one big bended patch difficult i think.

We initially made these precut fillers before reproduction firewalls were available. If someone had a nice AC style firewall and wanted to make it into a non AC style firewall, this allowed someone the opportunity to use the kit to avoid having to cut the sheet metal and the slugs fit tightly to minimize the welding required. With the number of people doing resto mods, we are now selling more to this market as many do not want to completely cut out the firewall. We made the kits for the 66 to 70 B-Bodies and 70 to 74 E-Bodies.
I sent you a private message with my contact information.