Looks good I did the same thing a few years back to a pair. I didn't primer and just used a cheap rattle can of Duplicolor. I retired the car to parts duty over three years later and though the paint wasn't nearly as fresh as the day it went on the re spray didn't have a single chip missing from either cluster. I'm thinking you should be good to go for some time. However the rears are about the only thing you can re paint and re use on the the car if your looking for a complete shadow line look. Drip rails, side trim, window trim etc. doesn't fair as well on a re paint. The M5 trim I believe can still be purchased new.