for anyone in future wanting to clean cam housings you will want to clean/soke them in cold parts and carb cleaner, by safety clean company they use to do a 20 liter drum with internal pick up tray we use to use this in a Porsche shop i worked in mainly to get wurth orange sealant off head to cam housing faces also for cyl heads it removes carbon well, we mainly wanted to dip the cam housings to clean out oil squirter tubes that feed rockers as they can block up and wear out cams and rockers this will save you excessively sanding faces, i would not be a good idea to machine faces as you should only lightly face them off in your cleaning machine with a honing stone with petrol or cleaning fluid just to remove any burs or dents you would anly machine them if you had issues with warpage cam won't turn you will then need to precisely measure head heights barrell heights and block level deck height