See all the info in the FAQs on scope bases, there are numerous bases and ring mounts available, most will be mail order/online tho unless your dealer will order one for you, the H&R base is the most popular, the Leupold is almost as good, but a little shorter, stay away from the Weaver #82 if you can, even tho it's commonly available locally, the 1" flat spot at the rear doesn't make for good scope mounting usually, it's best to have the rear ring as far to the rear as possible.

Tim