Sorry, I have a stainless fetish.
Me too! I just spent a ridiculous amount of scratch swapping out my old polysulfone QD's to the stainless ones. They only work slightly better, but they look so badass. Worth every penny. I just have more that 2x the money in QD's now than I did in my entire first real 3 vessel 10 gallon system. Mmmm... shiny...
That being said, I'd definitely assemble then clean/paint. Take that with a grain of salt, I only have a burner on my kettle, the HLT & MLT are both electric.