Engine looks good.
about the area were the intake gasket sits, just take a wire wheel and clean it all off, as long as its smooth its all good, you probably wont get the marks out of the heads.
I wouldnt worry about inside the intake runners, maybe take a vacuum and try to suck up the loose stuff, but that sit, hard to clean that without taking the head off and dissambeling everything.
and with the exhaust manifolds, get yourself i nice big breaker bar, and a 9/16 Socket, Lots of Penetrating Lube (NOT WD-40) and they should break loose.