Avoid the Extreme Rage plates. They rust and they wear badly. Go with a belsales, shocktech, or the like if you're going to go with a roller sear. They're really smooth, and you won't have to worry about durability. If you go non-roller, go plated. A nicely annoed plate may look good, but they aren't anywhere near as smooth. It's not worth it.
Nelson spring kits are compatible with some cockers, but not a trilly. If you want a spring kit, grab a cocker maddman kit. They're easy to find, and should have you covered (except for the valve).