I would sand it down with 220/320, hit the bare metal with rattle can self etching primer, get some PPG "shopline" (the cheap stuff) epoxy primer 1 pint, body color base 1 pint, and their "general purpose JC60" clear 1 pint. Pick up a cheap HVLP gun, take it all the way apart, soak it in thinner/reducer, spray a decent amount of thinner through the gun, and spray away. Before you spray degrease the hell out of the bay with "prep all" or similar, tack rag it, and practice on a piece of plywood or sheet metal of cardboard or something to make sure you have a decent hang of it. I did that and it cost me right at $150 not including the gun (~$30 if you go cheap), it will look better than rattle can I promise, and body color just looks soooo much better in the engine bay IMO. If you wanted to spend less, a one stage paint may be a better choice
- oh yeah you need a water filter inline before the spray gun too