they were on when i bought it. the guy i bought it from said they were from the original 390. and they certainly look like them. but maybe they are the stock clevland ones. if so what is the sequence anyone?
Top is a 351C valve cover, below it is a 390 head. I think you see that they will not work well together. Even though you stat the opposite condition.
But as for your main question. The exact torque is not as important as even torque. With new cork gaskets I have had excellent results by stating at one end and tightening until snug. About 10 to 12 ft.lb. Do not over torque as that may bend the sheet metal and cause a oil leak. Good luck.
A good friend of mine, a PRO-STOCK engine builder told me years and years ago to lightly snug the LOWER screws 1st., then move to the UPPER screws. His thinking is that by doing such you will get a better seal on the bottom where most leaks occur. Kind of think as the lower portion of the cover being on a hinge, snug first then move up to the top, and when tightening the top you will be snugging the lower too.