I got lucky and picked up a NIB stainless Winchester Model 70 in 375 H&H for $750. I'm putting a McMillan Super Grade fiberglass stock on it, and I've also read that it is advisable to replace the rear sight. Which one would be a good choice? I see several models made by NECG on Brownell's site. Is the single leaf sight the one to get? Or maybe I should order the one Winchester put on their Safari Express?

I like the NECG, but I am not familiar with the other one you mentioned. That is a good choice in a stock. I redrilled and tapped the scope mount screws for #6 screws on mine and had it Nylited and am pretty pleased with it like that.