engine crust

Hi. I just took apart my 350 junkyard engine. It is an '87-'92 Chevy 350. When I took it apart it had a ton of black engine crust (carbon deposits/build-up?). The black crust looks like coal. I really don't have enough money to take it to a machine shop, but I am willing to spend some extra time to clean it. The valves are colored black and it seems that the entire engine has some kind of exhaust problem because everything is black or has this black crust. One port on the exhaust manifold was plugged up with this crust. My plan was just to replace the gaskets, put on a new intake manifold and carburetor and be done with it. I am planning on using this engine for no more that about 5 years since I will be able to afford better then. What should I do about this?