I second geb324's opinion! It's gonna be a lot of work if you have never built a lock before.
Not saying at all that you can't do it, but you need a good lock building reference book, especially if there are no references on the backside of the lockplate to help you locate the holes.
There's a lot of holes for you to drill and get lined up perfectly. The geometry of the internals matters quite a bit for it to work properly. Some of those castings look a bit rough and will need to get filed/stoned and polished.
As mentioned, you are also missing the frizzen spring.
It's certainly above my skill level, so I won't offer any building advice...
There are many on this forum who can give you good advice. Artificer comes to mind for locks.
Good luck with it, and please post your progress, I'd love to see how it goes.