Does this 5.9 Magnum look ok?

Here are a few more pics of that piston. Should I clean the pistons? The one spot on the piston scraped right off the other part appears to be aluminum as magnummopar said. Also what would be a good way to clean the gasket material off of the block where the head gaskets were at? Is there any kind of cleaner I can use? Some of the bores did get a little dirt in them when I pulled the heads, what would be the best way to clean that up? Would it be wise to just leave that piston and bolt on different heads and a cam and it run or should I look at the piston? Its a budget build but I want it to last and run good. Also those numbers on the pistons are they just the factory part numbers? Thanks