It was the base-line model...and being a Sears-marked gun instead of in Ithaca Trademark, it's value in the very nice condition yours is, is about $125-150...might get more at auction, but probably not much more as it is a true Single Shot...and few want to deal with that these days unless they are Antique Buffs trying to fill up the holes in their collection.
If it was the Deluxe w/ gold plated hammer & trigger...or the Presentation Model w/ all the bells & whistles...lot more $$ involved.
Basically you've got a good solid cheap shooter. Great to train your wife/kids with. That's about it.