[1969GPSJ]

With my 62 casting number heads, many years ago, I used a pair of galvanized steel pieces (thicker than shim stock, but not so thick as to upset the intake manifold seal) to block off the exhaust crossover. It probably had 40k street miles after these were installed. When I took the engine apart for the current refresh, both of the galvanized plates looked almost pristine. The cylinder head side had some exhaust soot on it, but there was no discernible wear, and the galvazing was still noticeable on both sides of the metal when I cleaned them up. Certainly, the best way to block them off with factory cast heads is to fill the ports with molten aluminum and hand blend the bowl area. I had not paid attention to the best way to plug the crossover for either the Edelbrock or Kauffman D port heads since the ProFlo4 intake I have for my current build does not have an exhaust crossover at all. I would imagine that if it were necessary to plug that (relatively) small hole, a threaded pipe plug (of a similar aluminum alloy) might work ok as long as you are careful to ensure it is tapped and installed so that the plug can not drop down into the port.