Hey Runar,
Lemans are great guns. For a good knock around ,"Git'er done", work horse kind of gun, Lemans are hard to beat !
I have one myself, built on a early 1970's Douglas 1 1/8 .54 cal barrel, cut to 31 inches. Weighs 13+ lbs. but holds steady and is probably the most accurate gun I own, bar-none ! ( including my cartridge guns !)
I've built a few Lemans for friends and I used the Siler Mountain percussion locks. The lock plate has enough room to allow for profiling the shape a little better (imho), but you find Lemans with several locks in them. Whatever Mr.Henry could procure I suppose !
Have fun with your project, I'm sure we all will watching your progress !! always do !
Mark