i have been running these valve covers on my windsor for about two years, got them from Lee Holman himself up at his shop by the airport, along with a tour.
They told me that i neeed to slightly elongate the bolt holes, then push the valve covers up slightly to clear my Crane Roller rockers. I did that.
I have just removed one, to polish up the fins a bit, and clean the sandcast part. I noted that there is some light wear on the inside where about four of the rockers have rubbed on the inside, despite my moving the cover up about 1/16th of an inch. So took out my grinder and took off a tiny bit more at the wear spots, and put it back on. I plan to do the other side soon.
I like them because the are a flat top valve cover, make the engine look wider. Plus, a nice place to put the beer can when i am under there tweaking one thing or another. I don't know if my roller rockers are bolt or stud.
I did not worry about a bit of aluminum getting into the engine, i use a no-bypass
oil filter.