An easy way to brace the cab front side to side is to bolt in a brace using the lower door hinge bolts. That would insure your cab stays in place. It would depend on how much of the floor and toe panel you need to replace whether you need to do that, but it's cheap insurance. As archburycontrol mentioned, the Factory Assembly Manual has dimensions of those bolt holes referenced to the center line, so you can check before you get started.
I used a piece of perforated angle that I had laying around, and it worked will for bracing that dimension. It was one of the first things I did before any welding took place. Here's a couple of pics.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
