When I port "the other" harley engines, I use kibblewhite guides if a lift of over .530 is involved. I really like the black diamond valves,which I think are nitrided stainless, are great. They will build your valves out of anything on request, and special order aren't that high. I have had them build oversize guides for me to repair wallowed out aluminum heads, this way the seats don't shift from the heat of welding.
Cotten, just for your info, Jim's just came out with their ovn line (Advanced Valve and Valvetrain) valves and guides.....I knew you would want to know....I'm ducking and running...jb