A vibratory cleaner, with a user that knows what each media does is the correct answer.

Years back I ran into a rep for Wheelabrator corporation that had five such machines in his own personal pole building.

The guy was a car guy too. He could reproduce any surface finish on cast metal. I would give him my parts and he would drop them off to me a week later. Even had him run some tarnished supercharger blower scoops through the process and they came out looking fully polished. If you looked close with a magnifying glass you could see the micro scratches, but for a drag car, they were fine.