Mocking Up Firewall for Master Cylinder Studs

Ok here's the back story. My old firewall was swiss cheese. To get the aftermarket/GM power booster on there the previous owner cut 4 new holes on the firewall and the brake pedal assembly cutting off the studs. As a fix, my friend and I decided to cut off the mounting tabs on the brake pedal mount and make new mounting tabs utilizing bolts as studs. I had already made the tabs. After the tabs were welded on the brake pedal mount, we were going to mock up the holes originally for the firewall. But as of recently, it doesn't seem like my friend is too interested in helping me with my car (now no access or skills with a welder to weld tabs on there) so I bought the newer brake pedal mount instead. Now I'm stuck with little tools and skill trying to tackle this on my own. :/