I went in the persuit of the same thing a few years back, finally found a set of Redfield 512032 SR #3 RUGER #3 CARBINE
Within hours of finding these I had a PM that informed me the No. 1 Varminter bases from Ruger work with the #3 as well.
I haven't tried this, but it's a maybe and sure looks correct. YMMV :wink:
FYI: My notes show, the difference in the front/rear base heights on the redfield is .128(.507-.379)
EDIT TO ADD THE FOLLOWING INFORMATION:
NOS Ruger Bases (SC-24) .126 (front/.277 - rear/.151) These measurements taken at the thinnest point/ centerline of the mounting screws.
-OR-
Over all thickness Rear .233, Front .349/378 averaged out .3635.
Take the average of the front .3635 minus the rear .233 = .1305
Conclusion: Ruger NOS SC-24/ thinnest= .126, thickest .1305, average .128 +/-.0005
Redfield .128
Note: the Redfield bases were easier to pick a place to measure, the reason for the single measurement, Milled out of a single piece of material, whereas the Ruger bases are cast.
http://shopruger.com/Scope-Base-No-1-Varminter/productinfo/90004/