My advice, get hold of a new gasket and four spark plug seals. May as well change them when it's apart.
Also, you should probably strip everything off, get it scuffed to about 180 grit for decent adhesion, and then get the entire rocker cover into some hot water with a load of washing up liquid, and scrub it inside and out with a stiff brush. Oil from inside will not only stop you from getting masking tape to stick around the various areas you should be sealing off, it may also contaminate your spray area. Re-wash until you are confident that oil isn't an issue.
Make sure you dry it thoroughly, all nooks and crannies, use a heat gun to make sure.
Then mask a skirt around the bottom, mask off the areas that need to remain metal, and block all holes through to the inside. Overspray to the inside might not do your oil any good when the paint breaks down and gets into the system.
a stack of 2p's is handy to sit on various areas and block them off.
High heat etch primer is a good idea, as it is an amazing metal protector and adhesion promoter.
Apply the wrinkle paint lightly at first to create a tack-coat that your more confident coats will go over easily afterwards. Use the heat gun on its low setting from about a foot back to evenly warm over the painted cover. The wrinkle will appear not long after. Keep applying coats until happy, and keep it warm,
If you can keep your car in a garage overnight, you don't need to worry about getting the rocker cover back on same day. Worryingly, if you look at the windscreen angle, any rain that may occur, will run straight down in the direction of your naked cams, and your plastics and ally shield will probably be missing, having removed them to get the rocker cover off.
The longer you give it to cure the better.
Best of luck.