This is the place that I sourced one for my SPF (used as a remote clutch fluid reservoir to replace the plastic Wilwood unit).
http://www.streetrodstuff.com/Products/76/
They sold me just the reservoir but as I recall it was a little expensive ($90 range)? I then had to have a bracket fabbed so that it extended away from the firewall enough to clear the throttle rods (thank you, Rob Frink!). See my gallery for pics...there might be one or two in there.
-Dean