Chambers is the best for that type of kit, however, you shouldn't use an English lock on a Germanic gun.
Yes, do your research and do not buy a kit (they are out there) with the wrong lock for someone who is historically inclined. Seems ALL the makers of "Tennessee" or "SMR" kits include a Germanic lock, but you'll be VERY hard pressed to find any originals with such lock.
Do it right. The wrong lock on any style gun will scream to the high-hills of those who study these things that you assembled a kit, and didn't understand what an original looks like.
Mr. Chambers will supply you a correct lock, and most of the kit sellers will substitute a correct lock for you, IF you know to ask. And now you know. Best of luck and welcome.
on re-read I see "siler late ketland" I'm not sure what that is.
Oh, so they make an English externals with Siler internals--that's different. No big whoop on internals. It's the pan and plate and cock that must be correct. "Siler" generally refers to a Germanic lock, and it wrong on a gun school that utilized English locks. Ketland is of course, an English lock.
I'm no student of the school specified, so I'm not arguing for one or the other for your application.
You have to know which is proper. I never bought a kit.