I typically recommend someone buying the best and most expensive scope they can, EXCEPT when talking about rimfires and air rifles. It's not like you are going to be shooting 300yds in near darkness with them. A plain ol 3x9x32 Golden Antler Tasco is about the perfect weight and size for a 10/22. I also agree with Bullz, save yourself some headaches and forget the 3/8" dovetail (or "air rifle groove" as it's known) and go ahead too the Weaver sized base/rings. For the last several years Ruger has included the bases with the rifles and the bases have both sized grooves on them. Most of the Weaver rails for the 10/22 are likewise "dual sized".

Good luck,
RA