What I said above, but a few more thoughts.
First, after you remove the parts, line them up outside the gun and make sure you understand how they work together.
You can lightly stone the surfaces involved, but with an old gun they are usually pretty smooth and the problem is a long trigger pull, not a hard one. Plus, if those parts are case hardened as I think they are, cutting through the case hardening will make the parts soft and they will fail.
But when you try to shorten that pull, you end up with the situation I mentioned.
I STRONGLY recommend you not try, and learn to live with the trigger. But if you must work on it, then go very carefully and take off only a little at a time before reassembling the rifle and testing it.
Work slowly and don't become impatient. (It is this kind of job gunsmiths don't get paid enough for!) Also remember that parts for the old guns are hard to get, and expensive, so if you ruin the sear or hammer you might have the rifle out of action for a long time. (New parts won't interchange.)
Good luck!
Jim