Rodger, Let me tell you a little about my experience with lead. Your goal is to get the fly down and down fast. It's very easy to do it to fast and have the thing dragging on the bottom. There is no way now I would put wraps of lead on a hook for the full length of the hook. It's a tremendous amount of wgt. It also makes the nymph look like it's on steroids. Start with a single length equal to the hook back, tye it in parallel with the hook, and see if it sinks fast enough for you. Or maybe half that, this is an area where less is more.
Also I think that you don't really cast wgted. flys the same as dry/wet flys. I would say that fish that are feeding subsurface are much less wary than those feeding on the surface. So you can get closer; a good roll cast is often good enough.
Let me also add that a good wgted. fly to use is tying thread the length of the hook, coating it with 5 minute epoxy and rolling it in gravel. Add a black or peacock herl head and fish. Let the epoxy get gooey before you coat the hook.