I have inherited a compound bow. It is an AMF Wing Impact from what I can make of it. The side of the bow is marked IMP-1420 60#, it appears to be written and covered by the clear coat. I do know it is from the mid to late 70's to early 80's. How could I find an approximate value of this bow?

IMO it's not going to be thousands, lucky if it's more than a hundred. Wing was better known for it's recurves than it's compounds, and to boot yours is an AMF, which bought out Wing and things went south from there. Throw it on e--- with a hundred dollar minimum and see if it goes.