Very tough to say given that info but a wall hanger that looks complete will almost always bring $500-$600 even if it is missing internal parts. A complete, function gun is almost always at least $800.
A pretty decent 38-40 octagon rifle can usually be had for $1500 or so. Complete poor condition, but functional, guns seem to be fairly available at about $1000.
Alterations, broken/cracked stocks, bad bores, etc can make a big difference too. I wish I could offer more help. Good luck.
