I own a Grumman Sport Boat. The Grumman Sport Boats have always had the closed decking over the bow as seen in the picture MX posted. The stern section also has the reverse flare at the transom.
So that’s not any kind of Grumman that I’ve ever seen.
It looks like a really nice boat. These small, narrow alum. boats can be highly sought after. The Sport Boat, the Alumacraft Ducker, these boats can have a cult like following.