I bought a couple of mercruiser 250 inline heads on ebay and they have 72. something chambers on them, real nice one of them was barely used, still had tight valve guides, I ground out the valves to fit 1.88 intakes. worked really nice. did it with a vintage valve grinding set by hand. Did a three angle cut on seats and added stainless vales, read that the stainless valves work will with cast iron seats.
