I'm in the middle of restoring a pre-Anniversay Speed Graphic, the base plate is aluminium, however the corrosion was severe and unless all traces are removed would continue to deterioate rapidly.
So in this case the base plate and back needed to be heavily cleaned with coarse wet & dry, then a wire wheel brush on a drill used to clean the badly corroded areas.
The aluminium parts were then spray painted with an appropriate primer which keys with the rough coarse finish. Then filler was used to repair the deep areas which had corroded, finally finer wet & dry and more primer and the parts are ready for 2 or 3 coats of semi-matt black.
Ian