Sorry can't help you with '39 parts specifically, but I've had good luck finding oddball parts from Randy Steele at EPS parts. He has a website here:
eps parts
Other parts (break wheel cylinders, master cylinders, ect) can be refurbished through White Post restorations. They are a really nice restoration house, but on the side they will ream out and press stainless steel inserts into old oddball hydraulic parts.
Also, you HAVE to post pics of your project. Regardless of condition, we are all very curious of what you got.
Sholin