Does anyone know where I can find a head and spike for a linstock? I can find a wooden shaft for it myself. Doing a web search on this stuff gives me links to sets of cannon tools, complete linstocks that take a long time to make, antiques, and (most of all) stuff completely irrelevant to cannons or even firearms in general.

I served on a cannon when we reenacted the Rev War back east. Try google search of Rev war or War of Independence suttlers and see what they have.

I think you might try Godwins in PA; Smoke and Fire (in Ohio I think); or look for War of 1812 or French and Indian War suttlers.

Also check out the British Brigade Rev War group, find out who is the Chief of Artillery, and email and ask your question.

You might also try similar searches for Civil War suttlers and the arty guys in the umbrella Silly War organizations.

Here's the link to the British arty groups. These guys are the best of the arty reenactors. Give one of them a try.

https://www.britishbrigade.org/our-units