Is It stupid to say that the cam lift is the determining factor. The valve fully open due to cam will vary on setup. Some might foul and some may not.

I've seen some people grind a corner off a rocker on each bank to clear the covers, but I'm not sure how recommended this is. One of my cars has this, but I've not had this particular engine running. The picture shows what I'm talking about. Obviously, the rockers are currently in random positions, but from memory the modified rockers go furthest forward on the left bank, and furthest back on the right bank (drivers side).