Chuck, I ran a home designed triangular system similar to what you described that used all GM parts and tied the lower dash, steering column clamp, firewall together over about a 10" span and it worked great for several years that I had the truck. Like anything else, if you do it right and consider all the forces you shouldn't have problems with the firewall cracking from fatigue. Phat was right in that lots of folks don't have a clue and just bolt up to the firewall and dont consider how much force a person can develop on the pedal when stopping not to mention how many times it is done in a given trip.
