Norm, as I recall there are 2 half-moon shaped sections at the rear of the valve cover gasket that need to be aligned properly to ensure a tight seal. Do whatever it takes to "see" back there to ensure the gasket is aligned properly. I use a mirror and a flashlight, but whatever works for you. You might try installing the gasket on the valve cover and then setting the valve cover in place atop the head. Torquing the bolts to the proper value means nothing if the gasket is misaligned, leaving gaping holes.

__________________
Fred Hoelzle