Combine crumbs, sweetened condensed milk, rind, juice, and vanilla in a medium bowl. Add 2/3 cup coconut, and beat with a mixer at medium speed for 1 minute or until no longer grainy. Add sugar, 1/4 cup at a time, beating until well combined. Cover and chill 20 minutes.
Shape crumb mixture into 24 balls, about 1 teaspoon each. Place remaining 1/3 cup coconut in a shallow bowl; roll balls in coconut.
Note: Refrigerate balls in an airtight container for up to one day.