Let's settle this once and for all..

Are you talking about the holes under the exhaust ports?
I just cleaned mine really good and used a zap from the mig welder to seal mine and it worked flawlessly.
It only took about 10 minutes for the whole job including a quick pass with the air sander to level it off.
It was like filling in a spot weld hole in sheet metal.
For those people that will say ''You can't weld cast iron with a mig'', I am a journeyman welder and just quickly filling that hole won't matter, it's for sealing and not for strength.
The small area between the outside where it was welded and the inner port will fill up with carbon in no time anyway, there is no need to be elaborate and over think the small hole in the port will cause turbulence.
A lot of them were filled with carbon over the years and were plugged anyway, that's why some times you can get away without plugging them from the outside.
That's what I think happened in your case..........