Dang it Pat, another boyhood ambition crushed in the ugly jaws of practicality. My wife has dashed many such dreams by simply asking things like "and what the hell were you going to do with THAT?" The last one was a real '50's vintage Victory Siren.
http://www.victorysiren.com/x/index.htm
As an aside, I have helped crew an acquaintance's canon. It is a modern made replica of some kind of Civil War field piece. The new ones are commonly made with a bore size suitable for concrete filled soup cans. Pretty cheap ammo, and they work just like a .38 or .45 wadcutter when punching holes in targets. I don't remember all of the details (it's been a few years) but I seem to recall a foundery in Idaho was casting the barrels. My acquaintance made his own carriage. And yes, shooting canons is fun. Oh, and before anyone asks - yes, I was going to buy one. Que wife: "what the hell are you..." Wives just don't understand these things.