Stock or mild builds with flat tappet cams like at least 1200 ppm zinc. Major builds more, due to stronger valve springs etc.

I run 5W40 Shell Rotella T full synthetic which has close to 1400 ppm zinc. Most, if not all, heavy duty (diesel) motor oils have a good amount of zinc. Racing oils too, but may not be suitable for every day cruising. www.bobistheoilguy.com has tons of info.