Condition is important, but the year is important too.
IMO, the Grizzlys of he '60's will bring more than the ones from the '70's. If it is a flat coind '70's it should bring more than a raised coin
I will be surprised if the screws on the bak of the sight window are factory. Never knew Bear to do that. More probably the owner installed brass inserts to accept the screws. There were so many differnet sights available at that time, and the hole spacings would have to be perfect, and they were all different.
I am by no means a Grizzly expert, but those are my thoughts.
In any case, there is no "book value" on old bows. Theya re worth what someone will pay...no more, no less. The only way to really know what it is worth is to put it up onn e8ay and see where the bidders place the value.