It sounds like it's time to set up a head on my valve seat and guide machine so I can get the alignment of the plug holes all the same, and try it. It should be fairly simple to spot-face the gasket surface so the bigger seal ring will work, and then use a piloted drill bit to prepare for tapping a new thread. Unless I end up with a water cooled combustion chamber by hitting a coolant passage, it seems like it would be a good way to enhance the dwindling supply of 216 heads. Once I get a running prototype going of a full pressure oiled 247 cubic inch "216" the demand for these old engines just might increase dramatically.
Jerry
