Make sure the cover doesn’t have dimples where someone previously overtightened the screws. Straighten the tinwork if you do see this.
Also - lack of visibility at the rear of engine can make it tough to discern valve cover leak from side cover leak. I recently replaced my valve cover gasket, but had planned to also do the side cover…thinking I had a leak there as well. The valve cover gasket seems to have cured all the oil in that area you’re describing.
You will get all manner of opinions on what sort of “goo” to use and on which (sides) of that pushrod cover gasket. It’s hard for me to imagine installing it without some sort of goo, on at least one side. I tend to use permatex super 300 for things like that.
