Hi Flintlock1640
I'm surprised Czerny's offered this as-is on one of their auctions. It indeed appears to be a pistol from Central Italy. And the lock looks like it was what we sometimes call the Roman style miquelet. But I would date this pistol somewhere around the Early to Mid-18th Century. By this time, the lock plate for the Roman locks were taking the shape of typical flintlocks. And the lock mortice shows evidence of this. As well, note the mortice has no cut out for an "internal" mainspring. The mainspring being on the outside of the lock plate on the Roman locks, similar to the Spanish miquelet locks. My guess is that the lock, lock screws, and trigger guard are missing because they were catabolized for use on another gun. Too bad. But more common than you would first imagine. The stamping of "Lazarino" on top of the barrel looks a bit hap-hazard, and is likely a period forgery. Unfortunately, this was a common practice with Italian guns during the period.
Restoration: I suppose the wood stock could be salvaged. If there is anything I've learned about our hobby, it's that most anything can be done given enough time and money thrown at the project. LOL But I like Pathfinder's idea better. Using the existing barrel and hardware to make a custom pistol.
BARREL: The barrel can be sent to Bobby Hoyt to have the breech plug removed and inspected and the bore burnished smooth again. Worse case scenario is a new barrel liner.
LOCK: A Roman style miquelet lock would not be difficult to locate. Czery's has them in their auctions most of the time. And pistol size is easier to locate than shoulder gun size. The Roman locks are common enough that you could probably get one for no more than the cost to have someone assemble a kit from The Rifle Shoppe. Speaking of which, TRS shows they have Italian style lock kits available. Which is another option. Just keep your eyes open for Czerny's auctions (and Herman's also). You will likely see a good condition, original lock in working condition for around $300.00. Just make sure it's pistols sized, which most offered are.
STOCK: I would start with new wood. European walnut - for pistol size - can be had at a reasonable cost. You have the original stock, so you know what it's supposed to look like. Using new wood would likely be much easier than trying to retrofit a lock to the existing mortice, and all the small, tedious work of trying to restore the stock.
TRIGGER GUARD: Would be almost impossible to locate an original that could be used. I've seen iron hardware offered at Czerny's in the past. But very rarely. However, the iron Italian trigger guard from kit #710 in TRS catalog looks like it could be modified and used.
Anyway, just my thoughts. Let us know what you decide to do so we can be on the lookout for you. LOL
Rick