Steve
I built my frame from 2"x4" 1/8 wall steel tubing. It worked good but I would use 2x3 tubing if I did it again. I bought a pair of 32 Ford front frame horns for it and they were 2x3. I have a CNC machine so I narrowed one end of the tubes to 2x3 so I could weld them on. It also gave me clearance for the front buggy spring. The steel was around $65 and the frame horns were $59. I used a model A front crossmember and a 32 Ford rear crossmember. My center crossmember/trans mount is made from some 1x3 steel that was leftover from another job and it's removable.
AL