How to date an AVS carb?

Was digging around my Mom's attic above the garage and found an AVS carb that was on a 70 340 dart I had back in the day.Don't know if it was original to the car as I was the 3rd or 4th owner.Any way to date it? and what would it be worth cause I'm thinking of selling it.I know it needs rebuilt cause it's been sitting for 25 yrs.