@Pᴀᴜʟsᴛᴇʀ2 thanks dude -- BTW there wasn't much grit dust. I cut a round piece of cardboard to plug the bottom of the bore so that none fall down into the crankcase and, as you can see, applied painters tape over the deck to stop accidental dust from getting into the passages. then I wiped the residue from the bore with a cotton cloth and Seafoam , which did remove a lot of black gunk that got remove (I guess mixture of grit and bore buildup). but there was no dust