Scale removal from cooling system.?

I have a 1993 Mustang LX 2.3L and would like to know if there's a way to completely remove scale from the entire cooling system, without dissolving the rad and heater core. I understand the vinegar-coffeemaker trick is a bad idea here. I even noticed a small amount in the block too, and I'm concerned this will act as a thermal insulator somewhat. I have flushed the system well the best I could and used distilled water in the mix, but I'm concerned about the solid deposits that don't float away. Is there something that will dissolve only this?