Let's address several issues here.
First of all, thanks for joining us here on the Internet's best forum!
Second. This gun has three, not two, frame screws, FiReBReTHa. The rear sideplate screw is hiding under the top of the stocks. And all Model 48s had adjustable rear sights.
Third. The Model 48 is the K-22 Masterpiece Magnum. It was the first production gun chambered for the brand new Winchester cartridge. Winchester itself didn't even make a gun to shoot its new ammunition until well over a year after S&W introduced the Model 48. In other words, Winchester unveiled a new round in 1959 that it was not yet prepared to chamber in one of its own rifles. S&W immediately jumped into the gap, producing a revolver for the new round by the end of the year in which the ammunition was introduced.
Fourth. I've noticed that model numbering on the Model 48 is rather inconsistent as it relates to announced engineering changes. It seems not to be too unusual to see serial numbers on a dash 2 that you would think should belong on a dash 3. That seems to be the case here. Remember that the dash 3 change had to do with relocating a screw that was poorly placed - directly over the cylinder/barrel gap. It was moved on the K target frame guns to address this problem. But it seems that there were a bunch of frames numbered and shipped after the decision to move the screw that still had the hole drilled and tapped in the old position. Hence they were marked as dash 2. This seems to have taken place for at least a couple years after the dash three was released. I have no actual knowledge of this, but I wonder if S&W did not over-produce frames intended for use in the Model 48 line and found themselves running ahead of a market that was smaller than they had anticipated. That meant an overstock of frames that already had the sight leaf screw in the "wrong" place. Speculation? Yes. Possible? Also yes, in my opinion.
An aside: the Model 53 seems to suffer from a similar problem. Model numbers (or more precisely, dash numbers) seem to be all over the place relative to serial numbers on that model.
Fifth. In no way should this revolver have diamond Magna stocks. My dash 4 came with proper Magna stocks. They are now in my spare stocks box because the gun is currently outfitted with a very nice set of walnut targets with the football cutout. The revolver handles and shoots nicely with targets on it.
Good luck to you and your friend. I'm sorry for his loss.
I gotta be a good boy haha I can't save them all. It's like being at a pet adoption place. 
