Those ports are just asking to be ported out
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come ooooon
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, you've already got the head off
just kiddin' +1, bead blasting's the best but if you don't have one handy, scrape the hard stuff off with a tool of some sort but be careful, the aluminum is easily gouged. Finish up with some scotchbrite and some brake cleaner (wear gloves) or degreaser. My new favorite cleaning tool is a toothbrush. cheap and work well but they may not fit in them little ports.
Matt.