The sides and bottom of the channel were cut. After some hammer and dolly work, the resulting flap was recessed and the extra was cut off leaving nice gap for welding. After skip welding, grinding, and hammer crushing, the bottom weld was complete. The ends still need to be filled and welded, but that will wait.
I found the pedal pad. Turns out it is a Lokar SG-6008. Anyway, I cut out a cardboard piece to make sure the booster would not hit the throttle cable. Guess what? It did. So I heat and bent the pedal. I also had to drill a mount hole closer to the firewall (not shown in any of the photos). I will weld the support to the square tube cross piece as soon as I am sure I have enough pedal travel. But, before I can mount the booster and check it, I will have to flatten the raised channel in the firewall. The engine comes out the next time I get out to the garage.
I got lucky in that I was able to open up an existing hole to the 1/2" x 5/8" rectangular size required by the throttle cable. Once the cable was attached, the Allstar pedal assembly was put in its approximate location to verify everything is going to fit. The location of the pedal pad is going to drive me nuts until I find it, or buy another one.
I got up this morning and wanted to install my new Allstar brake pedal assembly. Problem is, I went looking for my Lokar BAG-6005 pedal pad and couldn't find it. There is a box somewhere with the pedal pad, my blue dots, and some bondo and other items which shouldn't be left in freezing weather. Not sure where I put it when spring hit.
Anyway, I decided to move on to the accelerator pedal. I fabbed up a bracket to mount a 1989 Chevy 1/2 ton pedal. Holes were drilled so that plug welds could be put in when I am filling the many other holes in the firewall. For now, the bracket was tacked in place. The pedal was modified to accept my surfer pedal cover. Note how the packaging was cut and taped to the pedal to prevent scratching.