Glenn, unfortunately Warne has discontinued their smaller Premier mounting system and so components are available only from ebay and bench fabrication. Talleys are still available and I imagine that the original G&H top-mount styles are still available from Billingsley (formerly Billingsley & Brownell).
IMO most modern smiths make their ribs entirely too high and awkward-looking. I build a fair number of single shots and have had good luck using low ribs that DO NOT extend back over the receiver, with the rear scope ring mounted immediately in front of the receiver. I'm 6'4" now, shrunk an inch or so in my old age, and I have no difficulty with eye relief using Leupold and other scopes, even with pull lengths well over 14".
An alternative recoil shoulder can be provided by milling shallow depressions (~ 1/16" or less) across the rib's top surface that match the full dimensions of the rings's bases. The rings then will sit down into the depressions and be locked by the shallow shoulders. Or unobtrusive horizontal cross-pins can be installed across the dovetail just below the rib's top line, to act as shoulders along the lower front corners of the rings. Don't forget the lesson of Paul Simon's Fifty Ways song...
Good luck, Joe
