As I have most of my engine taken apart pretty much for a head gasket replacement, I noticed it has, over the 8 years and 120+K miles, collected a fair amount of carbon blowby inside the cylinder heads and intake manifold, as well as oil crud on the outside.
Should I clean the blowby inside the cylinder heads, valve covers and intake manifold with Seafoam and what should I use to apply it? Possible options include but are not limited to abrasive wire sponges, wire brushes, rough shop rags and smooth microfiber cloth.
Pictures of the intake manifold are below. Please note that the excessive blowby buildup could be due to the fact that maybe my oil was mixing with the coolant due to the blown head gaskets as well as that maybe PCV was recycling fuel mixed with oil. But that should be outside the scope of this question. I do not have pictures of inside the valve covers, which has more crud than the cylinder heads (almost none) but less than the pictured intake manifold.