[Bill DeShivs]

Strong guns are collectable items.
There are Ebay sellers you might contact for more information. I doubt the Strong company you contacted has any relation to the original company-likely a dealer/collector.
Restoration should not be attempted by an amateur. There is much rust on the steel parts that needs to be removed to see if those parts need replacing.
The cast iron carriage could be safely soaked in Evapo-Rust to chemically remove the corrosion.

 

[Bill DeShivs]

Very nice cannon.