I had one. My mount was an over under type. You could see the peep and use the scope. Good idea, bad performance. I can't exactly remember the configuration, but it seems there was a large knurled nut on the side, it's only attaching point. Then 4 allen screws were snugged down to the top of the reciever. Acurassy sucked, somewhere in the 5" group, the point of impact would shift from time to time.
I would definatly urge you to go with the ranch model. That way you could get 4" groups anyhow. A dot scope would be a good alternative, since acurrasy isn't that great with a lot of minis, at least you have a fast alligning sight.
A gentleman posted somewhere to drill and tap the reciever so the 4 screws would work with the mount as well. This of coarse would ruin the value of the rifle, it seems the ranch rifle would be a whole lot easier. I hunt with a guy that had a bull barrel put on his. It shoots 1" groups all day. So I would assume that's where the problem lies with a factory Ruger.