From some Mopar TSBs:
Gasket Surface Preparation On Aluminum Engine Components
"NOTE: DO NOT USE METAL SCRAPERS GRINDING DISCS OR ABRASIVES TO CLEAN ALUMINUM ENGINE COMPONENTS. DAMAGE TO THE SEALING SURFACE WILL OCCUR."

Multi-Layer Steel (MLS) Head Gasket Installation Procedures
"Using a plastic or wooden scraper, scrape any large amounts of gasket residue from the surfaces. If necessary, apply additional solvent/gasket remover to ease removal.
If additional cleaning is needed, use a drill motor and 3M roloc bristle disc p/n 07528 (white) carefully remove remaining gasket material from head/block"

White is called fine by 3M, and they call yellow medium.

Personally, I would use any type of abrasive or power equipment as a last resort. At work, we use Plexiglas scrapers on everything, which us usually aluminum. Southwest Airlines wants only a specific scraper, which is a plastic softer than the Plexiglas, used on their aircraft. They tried using a cheaper maintenance company in Canada, and they used razor blades to remove seal on the skin. The entire plane had to be scraped. We got their business back after that.