Even among Kalezky collectors, I don't know if it would realize all that much due to condition. Knowing what the mechanical side of the locks looks like as well as the underside of the tube may increase the value. If it were mine, and I don't know if he would perform the renovation or what it might cost, but Steve Zihn of Wyoming turns out some pretty incredible muzzleloaders and he might bring it back to the state of a shooter. Is there a crack in the wrist?
I really don't know the date that the globe sight came into use but the mount seems to be of that variety and it may be that the sight evolved about the time of the percussion cap. I don't know of a globe type sight on a flintlock, but there could be. Can you send me a pic of the hammer back showing the nipple? The triggerguard bow may have also served as a rest. There may be a date or stamp on the under side of the tubes that helps narrow the date. The lock makes me think of Valentin Christoph Schilling or maybe one of the Mehlis craftsmen. Stamps on the underside of the tube would verify this. Let me send this on to GGCA's Mr. Richard Hummel and see if we can get some answers.
Kind Regards,
Raimey
rse