Most rust can be rubbed off of chrome with polish but to have rust coming thru you must have small holes in the plating. once you get it cleaned off you can wax and wax and wax and if will stay looking fairly nice oh time to wax it again. I have heard prices from $650.00 - $1200.00 for rechroming a 47-53 Chevy truck grill. The condition of the grille and the plater all changes the cost.
Mike