Yeah, I see your holes look bigger, the rear ones are way further back, and I see the cuts in the receiver. Not the same thing. I'm almost wondering if I could get my hands on one of those weaver mounts, just to see if that's the right pattern. And since they're there, I might even mount it. But I don't want to screw up a stock, so I probably wouldn't. But it would be interesting to throw a scope on.
I'm kind of irritated about it, as I didn't know about it when we bought it. My Dad went and picked it up and I really don't recall if the guy disclosed it or not to my Dad. Either way, there is a lot of other good parts on it, and I suppose it makes it a good "shooter" and not a collecter. Yet I've had issues with getting it to run. It might be as simple as my recoil spring though. I bought one new when I first bought it and it's 1/4" out of spec. And I haven't shot THAT many rounds though it. Maybe 500. If that. I need to start logging it. So anyways.... Yours is pretty cool. It looks like that mount is on the side, and might need some kind of bracket to attach to the receiver from that picture you posted. There are obviously two screws of some sort on that big bracket.