Here is what I like to do...........
Coat the valve cover side with aviation gaskett sealer,coat the valve cover with aviation sealant.
Then stick the gaskett to the valve cover..............then depending on if this is track engine or 100,000 mile street engine....if a track engine just lightly coat the head side of the gaskett with silicone sealer........possibly no silicone depending on how often the valve cover has to come off................if it is a street engine with a hydraulic cam that needs no valve adjustment I will put aviation sealant on the head side also.
Then snug the bolts down at about half the torque you will finally use...let it stand overnight ,then fully tighten the bolts down.....I have no idea what the actuall torque spec is for the valve cover...........I just use a 1/4 inch drive ratchet and tighten them down good and snug.......it is something you develope a feel for as to how tight ,then I also use blue loctite on the bolts and clean the threads really well first ,I usually use brake clean for the bolts and use a q-tip soaked in brake clean for the bolt holes.
Some would say that it overkill to do it this way ,but I very seldom have leaks and they stay put when installed in this manner.
I would think you would have to really go pretty tight to break the valve covers or have mushy thick gasketts to break the valve cover ears off from tightening them.........I also like to use the metal reinforced rubber gasketts ,but I am sure the reinforced cork will work fine also.
I did a quick search and 4 to 7 ft pounds seems like the normal recomendation for most of them.
I think you would be safe with 7 to 10 ft lbs considering your gaskett choice....but I would feel it out and if that seems too tight STOP.....
In my mind it would be better to have them too lose at first and have to tighten them ,rather than stripping/breaking a bolt off or crushing the gaskett.
Well thats my 2 bits anyway..........hopefully someone will give you the correct torque spec soon.