After much discussion with Bob and others, I finally decided on 4 3/4 inchs for firewall tube center to tube center on my pedals. The plans call for 4 inches. Too close and they hit the firewall, too far and the brake can overcenter at the extreme lock and completely lock the pedals...not good. In conversation with Bob, he said the over-center problem generally doesn't happen until the pedals are at 5 inches or more away. Even so, there are easy fixes for this if it happens.
According to Eric Newton Proto II was at 5 inches and I decided 4 ¾ inches would give me a good margin for safety for overcenter and still give me adequate rudder travel with the bigger rudder horn. The locating the mounting plate with a straight edge and welding was easy. I used a wooden block and clamp to keep the proper pedal set and used c-clamps to hold the assembly while drilling the holes for bolts that secure them to the plates. Worked great...a non-event.
