See if there is a vapor blasting service in your area, that's the best way to restore the original finish, in both looks and 'feel'. I do parts for people all over the country, but recommend that you use someone local to save the shipping, although aluminum heads aren't too costly to ship. Once blasted, an anti-corrosion coating like ACF-50 will keep them nice and easy to keep clean.
http://www.houstonvaporblasting.com
