It might be a little on the large side, I would guess, but the L&R back action lock would be an easy place to start for something like the boxed set, and you might be able to get away with trimming the plate a little to make it more like what you wanted. It doesn't look to me that there is much impossibly difficult work on one of those (granting that the small scale of some of them would present a challenge, and even finding parts might be impossible), and it would be certainly different when you finished, not to mention you'd be paying homage to a period of gunbuilding that often seems neglected if not outright shunned. There's not much wood to worry about and actually very little furniture either. I'd go for it, as it should make a pleasant little project between rifles.
