HELP WITH 104.98 CYLINDER HEAD

[rp930]

Just pulled this head off 1991 300sl. what in the world am I seeing. Coolant passages are blocked solid with paste like material. The reason for pulling head was oil in coolant tank. Per mr Roys advice I flushed system 5 times with tide. It seemed to get cleaner, but when I checked oil level it had gone down about 1/8" on dipstick. So I pulled this thing off(rough on an old guy). Has anyone seen one in this condition? I've done a couple of hg long time ago. The machined surface seems to be stained badly. My intention was to clean up and look for cracks before taking to head shop. Any advice would be appreciated.