An '87 Model 70 Featherweight is a very nice rifle, but Winchester guys normally prefer the controlled feed variety. The 80's push-feed Winchesters are very good rifles, I have one myself. Now, you have some kind of mounts obviously if it has a scope, so depending on what they are they might be worth a bit extra to some buyers. The 6 boxes of ammo?..well, they might be worth $10/box in a package deal, maybe less. A Banner on a 30-06 is not worth much to most knowledgeable buyers. Sling,?..worth nothing in package, I have a drawer full of old slings.
The thing that has killed the value of a lot of used rifles, even very good ones like an 80's push-feed Featherweight is the price of new rifles. A new FN built controlled feed Featherweight is about $780 plus taxes.
so, I'd say the whole pacakge might sell for a maximium of $600, the sling, scope and ammo are really just additions to make the package more attractive to some buyers, they don't really add a lot of value.