A worthy project. When you build a matchlock you indeed build it from scratch.
The one guy who does such here is Pukka Bundock. Search his posts for inspiration.
The one human being of our times who knew more about matchlocks than anyone -,period - was the late Michael Troemner, of Bavaria. Log on to vikingswords.com and search for posts by his site name, "Matchlock" I do not recall if you can search without being a member. No problem joining, but it may take a couple of weeks for them to decide on you.
Match locks come in roughly three varieties. An early 16th century one might be a "snapping" lock, in which a piece of punk (remember your evil childhood? Ask Daddy? Ask Grampa?) moved forward into a pan to light things up. These things are reliable and good for target shooting, and I believe Bundock has recently posted his building process. Later military and civilian guns used a burning rope, moved toward you. These include what the first guys in Jamestown and in Plimoth used. Simpler to make, I think.
I made one roughly 40 years ago. Used a rifled barrel. Took it to the Canoe Shoot in Michigan that year, all those hairy guys wearing tomahawks laughed at it - will that thing shoot?
I never shot better there, slowly squeezing that glowing, spitting cord into the powder pan. Hit the gourds slowly floating down river; also the thing did indeed go off. Heard a lot of "click click @#$!!&^% down the line. Not me. When ya gotta burning cord and some black powder you may be assured that there will be some manner of explosion, somewhere, sometime.
For your matchcord do NOT soak rope in saltpeter. I did, as I knew no better. Old ones were linen or hemp boiled in potash (potassium carbonate) to dissolve away the lignin, for a better glowing ember.
