Doug,
One more option to consider if you are interested, and that is a thermally activated fire suppression system. I have a buddy with an INTERMECCANICA ROADSTER ( reproduction of the Porsche 1959 356A Convertible "D" ) equipped with just such a system.
The company is Safecraft Safety Equipment, in Concord, CA. (
http://www.safecraft.com/MinstalledExtinguisher.asp ). They also have manually operated systems as well. I know that you already have the parts for your fire suppression system, but thought you or other CC members might be interested.
The automatic system may not comply with track use ... always lots to consider when making these kind of decisions ...
- Tim B.