I'm with Handwerk on this. I don't use the extended bases. I have tried a set once because I was led to believe they were the standard
930702 (matte finish lows). I bought them here (used without the package). Talley's work fine on pre 64's, but lately I've been gravitating towards the Leupold DD's. Here are some pics to give you an idea of one vs. the other:
Leupold dual dovetail mounts/rings:
Winchester model 70 with Talley lightweight lows (930702) and Leupold VX3 3.5-10X40: