I have two of Bud's kits I picked up in trade over the years. Unfortunately they are in far east Tennessee at the moment and I am in Texas until April or so. I do have one set of his instructions I can photocopy when I get back if you cannot find a quicker source.
When first building MLers in 1975, I assembled a small Siler flint kit that I bought from Bud Siler and although I've forgotten some of what I did, I do remember that the inside surface of the lock plate had cast in dimples showing where to drill all the holes.....I used a center punch to make the dimples sharper. The holes were correctly located when assembly took place.
The tumbler, sear, fly and springs were hardened as rec'd, but the frizzen was not seeing a pivot hole had to be drilled in ***'y w/ the lock plate. The frizzen is a fairly large piece to be heated evenly w/ a Mapp gas torch, so I took a length of pipe, threaded an end cap on, drilled 6 small holes in the end cap and used it like a small oven to evenly heat the frizzen which had a wire through the pivot hole for dunking in the 10w30 motor oil. W/ the Mapp gas torch the frizzen was heated from the open end of the pipe to orange-red for a couple of minutes and dunked in the oil. When cool it was tempered at 375 degrees in the kitchen stove { I had checked the oven's temp w/ a thermo-bridge and and it was OK. }
The toe and pivot hole areas were then polished and heated to a bright blue color w/ a Mapp gas torch. I still have the .45 LR that has this lock and it has head hit 100s of squirrels. Replaced the frizzen once and the new one worked just as well.
The reason I assembled this lock was because of the poor quality of those on the market at that time. I didn't receive instructions for its ***'y as I recall.
I don't think that assembling your lock kits are all that difficult....but I was a tool and diemaker at that time.
Good luck w/ your endeavor.....Fred