I picked up the new aluminum head yesterday after leaving it off last time I was here to be cleaned, dye tested for cracks and have stainless inserts put into the spark plug holes and thermostat housing holes. I purposely did not have it milled and, other than a couple tiny spots of very minimal corrosion that you can’t even really feel, it looks like new!
The one currently in my Patrician has had repairs around the thermostat flange area and still has much corrosion there so it took great effort a while back to get it to stop leaking!