Well i got my block from Brian today and i ripped open the box to check it out. Well i noticed the cylinders were dirty with loose dirt, kinda like chalky dry oil. Can I just blow it out with an air gun or do i have to really clean it out before i start up the engine?

 

It's probably carbon, from the cylinder head roof. Vacuum as much out as you can. I'd be a little worried about the condition of the engine.