I had just done the same procedure with my Toyota 2C, due to oil leak from valve cover. I thought it needs a retourqe, but the mechanic said it needs only to reseal the gasket. When he opened the cover, I noticed that the seal was already pressed down, and without any springy action, and the bolt is made of aluminum, and obviously does not need torque as it will break if more pressure is applied. The mechanic just made a good clean up of the edge (he did not remove the old seal/gasket) and applied Loctite Superflex White RTV (the drawing on the package suggest that it is used for flange), and retighten the bolt normally. It is almost a week now and the leak is gone.

In my opinion even red or black RTV sealant, the one used for oil pan will be sufficient as there is no high pressure in the overhead cam of my 2C engine; I don't know in your case.