Is your motor a windsor or a cleveland? If it is a cleveland, which heads, 2V or 4V?
I never heard of anything like that for a windsor. (I do know of the port plates for the Cleveland, I never heard of them being used in a car with shock towers because of the severe bends required in the headers to exit down.)
If it is a 351Cleveland,(which like woods said, were not installed in any 69s that I know of),could those exhaust gaskets be 2V gaskets on a 4V head?
There is a definate difference in the size and shape of the 2v to the 4V exhaust ports. I know that they usually leak like crazy if you put a set of 2V headers on a 4V head. Or use the wrong gaskets. I know this from personal experience.
A picture of what you have and a positive motor ID would be helpful.
my signature lines...not really directed at anyone in particular..
BE different....ACT normal.
No one is completely useless..They can always be used as a bad example