Hi Barud
That one indeed has a beautiful barrel and wood. Here is my assessment:
STOCK: As Cyten mentions, it's missing it's rear butt section. Also, there appears to be a large sliver of wood missing from behind and just forward of the lock area. Also, I can not detect any evidence that the barrel is pin-fastened to the stock. The slight darkening of the wood near the muzzle end tells me there was once barrel bands (maybe just one or two longer ones) at that point. It's possible the only thing holding the barrel to the stock is the breech plug tang. LOL
LOCK: A nice looking Turkish lock. Looks like it may have a date as well as the maker's mark. The lock appears to have been chemically cleaned. While this type of cleaning distracts from a collector's value, it doesn't really matter if the goal is to make a shooter. Also, it appears the grooves in the frizzen face are completely worn down. Assuming the lock is still in general working order, the frizzen might require re-hardening. So the lock has likely seen much more use than at first glance.
BARREL: A beautiful Damascus pattern typical of high quality Turkish barrels. It would be good to know the condition of the bore AND if it is rifled or smooth bore. A smooth bore is much easier to clean/re-furbish to shooting condition than a rifled barrel. Unless, the barrels are getting new steel liners. Then the bore condition is not really important.
IMHO $1,600USD is way to much for this gun that is missing parts and considerable lock wear.
Rick