A restored gun is always going to be a restored gun, and will never approach the value of a minty factory original gun. Restoration has to be for your own satisfaction, you will never get the cash back out of a gun that a proper restoration costs.

Congratulations on finding a fine Grade 4 Ithaca. What kind of barrel material? Krupp Fluid Steel? Damascus? Everything you want to know about Ithaca is in Walter Snyder's book --

http://www.shotgunworld.com/ithacabooks.html