One thing to look at on these valve covers, be it Offy or Waynes (I have a Waynes) is the lip where it contacts the gasket. Make sure it's flat. I had to have mine flattened to get it not to leak.
Set it on a flat surface and check it with a feeler gage. If you do this first it will save you the frustration of taking it off and fixing a leaky valve cover.
George
