This is my first big block, its a 454. I am cleaning up this motor and in the process of replacing the intake. In the center of the heads there are some (what I am assuming) smog related ports that are full of a thick oily carbon build up. What are these? I am cleaning them out as best as I can but am afraid of where the residual crap I cannot get may fall in to. My edelbrock performer intake has the smog block off. How critical is it to get these perfectly cleaned out?

Here is some pics:
http://img91.imageshack.us/img91/1062/454head1xm8.jpg
http://img91.imageshack.us/img91/4971/454head2gy1.jpg