Is it an acceptable practice to install engine gaskets onto the painted surface of the block? I'm specifically referring to intake manifold gaskets... common sense sorta tells me "no," but I'm curious if it really matters.

Not a problem. Slap 'em on there. Number of times I've put intake gaskets onto a head that's got over-spray from painting is a lot.

I go more with the no approach but i have heard of people doing it with no problem