Jim Are you trying to sell it ,shoot it,shoot it for noise om holidays and have fun?I went thru the same thing on my cannon.If you are trying to sell it you and only you know how much you have in it,are you trying to make a proffit or just get rid of it.The value is what some will pay for it at the time you are ready to sell it.
I like your cannon I would not touch your cannon .I like the character of your cannon it took years to make it look like that.If it is what you want just go out and have fun with it.
I was told to take the tube off and make a different carriage ,change the cast steel wheels ,I deceided not to polish it ,I love my cannon as is,I finally found the daughter of the man who built my cannon and said it was the dirty on .He had built my cannon as a shooter an built it with the cast steel wheels so he could take it out on the dirt roads to shoot it.he built it in 1952 i, it is a bronze tube .He built others that were very pretty and fancy ready to be put in movies etc.They all went to the grand kids that still own them.The daughter got upset whenI told her I had just bought a cannon with her dads name on it,she thought one of grand kids had sold on e of the other cannons.She then asked what it looked like and she said her dad had built it as a shooter.She finally got tired of having it around and sold it to a antique dealer who sold it to the man that had it consigned at the gun shop that I bought it from with no info on it.I joined he and they helped me find a lot of info.
Hope this helps you on your cannon,I hope you find out more info as I did keep it and shoot it and be safe AND HAVE FUN WITH IT.one thumb short