Those pics look nice. 1 thing tho....you're going to want to get those sinks as flat as possible. Also, watch out for the yellow resistor? by the mosfet sink on the far left. I have the same board, and couldn't figure out why my heatsink wasn't staying on the mosfet. Turns out the yellow thing was getting in the way. (Kinda hard to tell when the mobo is still in the case, and you got a giant hsf hovering over them) I was able to gently bend it out of the way and it now fits great.
As for the spray painting, my gut tells me it would be worse for heating, but the ones I bought, came painted and seem to be working great. Maybe if you could find a spray paint with a high amount of metal in it...