I had the same problem with the heads on my 428 Police Interceptor. Didn't want the heads of the plugs to show, remember Cobra engines NEVER had air pumps.
A machine shop here in KC said he could weld them shut. When I arrived, he looked at the holes and asked if he could install a cast iron pipe plug and then run it through the mill to remove the end of the plug.
Worked perfect. You cannot tell where the pipe plug is.
Plus it now looks like a head WITHOUT the air tube holes.
Just a thought.
Smoke 'em if you got 'em, tires that is
