Thanks mate, I brought the heads like that.......I was a bit surprised to see the build up of scale in them, The previous owner must not have run coolant in them?? I was just trying to find out the best way to clean them.
The only real/complete way to clean them is to take them to a machine shop and have them hot tanked. If you haven't put any coolant/antifreeze in your motor yet, use Evans coolant. It's a waterless based coolant (means no rust) has a greater temp range and its a lifetime coolant. This is the same coolant you'll find in NASCAR racers.
Here's their website http://www.evanscooling.com/
