To Okabow,
Manton is actually a little "fancier" than necessary, but you can file off some of the fru-fra and make it look more "barrel of locks" like, at least that is what I did with a Durs Egg, which is quite similar, but bigger. I've also looked at some of the small L&R "RPL" locks. Though they are intended for replacing Spanish Maslin copies on CVA's, some of them have styles very similar to what you might see on late flints (which makes sense if you think about the Maslin that was supposed to be copied).
To J. Talbert,
The Late Ketland worked on an 11/8" barrel with only trivial adjustment, so I'd guess it is large on a 3/4" breech. Tipping the tail of the lock down is an option seen on quite a few nice antiques, though, so it might work depending on the wrist architecture, drop, and so on.... If the design is late enough to allow rounding the tail of the lockplate, that gives you even more aesthetic flexibility, I think.
In general, I think the Chambers Late Ketland is a great lock and probably my first choice for out of the box functionality based on several I've seen, but I wouldn't forego the L&R Manton and Durs Egg either. I had L&R replace my old, tired Durs Egg cast main and frizzen springs with their new forged ones (requires a new hole to be drilled for the mainspring) at Friendship in the spring and I couldn't be happier. I had drawn the frizzen temper back a touch years ago, and it sparks every bit as fast as the Ketland on my chunk gun. The most recent times I've seen L&R locks, they are improving them quite a bit over just a few years ago. I think they have changed their frizzen material and now use forged mainsprings on all the new locks, so I would suggest checking them out before dismissing them completely. And if you like the style of one of the L&R's, a Bob Roller upgrade makes it one of the finest locks you've ever seen.