Hi Steve,
I have two rebuilt wheels cylinders from White Post Restorations. Part numbers C3OZ-2261-A and C3OZ-2262-A. They were sleeved and painted cast iron gray. Both are marked 38767 with small bleeder screw. I believe these are exactly what came on the GT350's. It was not cheep to have White Post restore. I'd like $500 for the pair plus the ride. You will need to add the two white dabs of paint to match the assembly line wheel cylinders. I can also add if you like, but will have to unwrap them from the sealed film. Please let me know.
Hope that helps.
Cory