First I suggest we change the title of the thread to at least narrow the focus to 289 applications or 289-302. If we don't then your going to adding to the mix/discussion another group of finishes such as the silver painted valve cover gaskets for example
Consider that the gaskets that came with your valance covers may have not been supplied by For or the same supplier as Ford used originally
There are original gaskets that appear fully coated, complete painted black and others that only show black on the top and bottom surfaces like other cork gaskets used on engines. Concerned that we will mix Shelby applications and Mustang/general Ford applications with one another. Your also covering allot of years while gasket part numbers changed suggesting differences in production. Example from Scoots post it appears that your car would have used C6OE-6584-A a change from the neoprene earlier valve covers Scott showed in his example. At the moment I can't recall exactly but for 67 the visible surfaces of the valve cover might have been painted with the engine for non-Shelby
We're going to need to figure out which valve cover part number was used for each engine and year rather than blanket the applications unknowingly. I know I don't have engine assembly instructions and blueprints for every engine combination. Only a couple and one won't apply to this focus