My thoughts on this are that when I get to doing the cab area of the body on my AD panel, I would cut the floor and firewall from the front of the seats forward out of a newer donor truck and weld it into the oldie, then fabricate the body mounts. This will give me the newer style pedals and a solid floor. I have seen the MC on the firewall with a SBC V8 so I know it can be done. Am I thinking wrong?
Also, seems I have seen kits for firewall mounted MC that includes reinforcements to stiffen the structure.