I'm doing my truck in satin black, it's going to be my only car and will sit outside all year round. In a couple of months time I should be painting and will document everything in my resto thread.
I'm using a light commercial paint by Selemix. It's 2k, its a direct product so can be used with a primer or straight onto bare metal, it comes in different gloss levels off the shelf (so no custom mixing and trying to match amounts of matting agent) and its hard wearing.
Have a chat with your local motor factor?