I am putting my motor back together this weekend and I have a few quick questions.
I was told to use copper spray on my headgasket, so since I have never done this before, I wanted to know should I go ahead and paint it now or do it right before I put the head back on?

Next I have a quick question about my DIY catch can. I have made a catch can/ crankcase breather box. I plan to install it in between the breather box on the back of the block and the intake manifold. Usually between this area is the PCV valve. Should I still use the PVC valve? Since the catch can has a filter on it to vent crankcase pressure, do I have to worry about a vacuum leak?