It looks like someone used allthread rod to make the pedal shafts. That stuff is soft steel, easily bent and not suitable for brake rods. This car was built by an idiot who does not understand the forces generated by a person standing on a brake pedal under serious deceleration.
I would order new Tilton (or Wilwood) master cylinders and use the shafts that come with them. These have a special shape with a washer and circlip that keep them in place. You can see in the picture below that only the end should be threaded. Make sure the cylinders have the same bore diameters as your originals. You can get these on eBay or Amazon very cheaply.
However, from your picture it appears that the shafts may be longer than the stock rods. I would look for a way to move the master cylinders closer to the balance bar. If that's not possible, I would have a professional welder attach a grade 8 bolt to the end of the rod. If that's necessary, I would also have him weld a sleeve over the welded joint to make it much stronger.
This is important (life or death) stuff and you don't want to screw around.
RS
