Oven cleaner is lye- - - -very caustic and hazardous to skin and eyes. I made my own hot tank cleaner by cutting a 55 gallon drum in half lengthwise, welding the two halves together end to end, and filling it up with water, 4 cans of lye, and half a box of Tide. I built a wood fire under it, and dunked an engine block, cylinder heads, and all the steel sheet metal into it. NO ALUMINUM! It worked great, and the leftover liquid got used to treat a bunch of fire ant nests!
Oven cleaner will work OK on small parts, and probably your cast iron cylinder head, followed by a thorough pressure wash but limit the time it's exposed to aluminum.
Jerry
