Hard to tell much but that fore end is definitely not original, so I would imagine the whole gun has been restocked. It's value will be strongly affected by how well that restocking was done. There was a bit of an upsurgence in collecting varmintized singleshots, especially highwalls, but whether that continues to be the case, I do not know. It does have a single set trigger, so that will add a bit to the value.

More and better pictures are definitely needed, including one of the breech with the action open. Is it chambered for a rimmed cartridge and if not, what is the extractor situation?

_________
BrentD, (Professor - just for Stan)

[Linked Image from i.imgur.com]