Chuck
Yes I did use permatex "The Right Stuff" around all water passages, for some reason the coolent just eats away at the gaskets and over time and heat cycles, the gaskets start to distort.
After the first full season of driving the exhaust started poping in deceleration, the problem was the intake gasket was so badly distorted it developed an intake leak. I changed to another set of Felpro's.
By mid summer of the next season I developed a water leak by the thermostat housing. The coolent backed out of the intake manifold bolt right by the water passage. This time I used Mr Gasket Ultra Seal. By September of the next year I developed a water leak at the rear of the manifold as coolent was leaking past the intake bolt.
The Mr Gasket "Ultra Seal" gaskets did pretty much the same thing. They failed around the water passages but did not distort around the intake port as did the Fel-Pro.
So after another local Cobra owner called Ford for the very same reason for his 351 , the Ford tech people suggested to use Victor Reinz composite gaskets. The jury is still out but there still on the motor and where running out of choices
Tony