I just refreshed a stock piston 400 with a pair of 516 heads. I haven't put it in anything yet but it sounds great on the start up stand. I used a small .440 lift cam as it's going in a truck. I have no knowledge of the older 4 bolt valve cover heads with the non integral rocker stands if that is what you have, but the 516 works great on daily driver type applications, and they came on everything from the 361 to the 440 in the mid sixties. I ran a pair for 5 years every day in my road runner on unleaded gas and when I took them apart the valve seats looked fine.
