Pistons/reconditioning

I used a gallon can of carb cleaner, the type with the soaker basket inside, and soaked the pistons one or two at a time for an hour or so, then flush them with clean gas and a little tooth brush action. Took all the crap off them. I would not use phosphoric acid, it'll chew the metal up, if you want to use a mild abrasive us super fine steel wool.

AS long as the pitting is below the wear surface I would not worry about any coatings. Just be sure that the bores measure good and match the piston dimension. I'd polish the pitted areas a little with the steel wool and let them go. I guess it depends on how bad the pitting is. Can you attach a pic ?