I just received my base and rings from Seekins Precision for my Rem. 700 SA and I have to say that the parts are excellent. They will go great with my Mark IV Leupy.
Glen is great to deal with, and his products are very good in quality and tollerances.
I had him make two sets of custom height rings for two different rifles. Excellent!!! They took a bit longer to get in the door, but he didn't charge anything over his regular price.