I am putting some small lower quarter patches on a '66 Mustang and will be blending the clear at the top edge of the quarter panels. The car was painted 20 years ago with black Imron (no clearcoat) and the "custom" painter added metalflake "until it looked right". It is not the big flake but it is larger than what is common today on late model cars. My concern is how to sand the blend areas. If I use 600/800 will it scratch the colors off of the metalflake in the single stage? Could I get away with a gray scrotchbrite and some scuffing paste? Thanks.