I believe that will be a huge issue. I have measured many stock heads including magnums and the most any head I measured would only allow .520 lift when the retainer hit the valve guide. Duration is a non issue. Valve lift is the problem
He says in a post a few down from the top that they are EQ heads. Wouldn't those have enough clearance? I'd like to think so since they are sold as a "performance upgrade", but I am not familiar with them enough to know.
