So, my 451 has been working great. I've run it for almost 2 years, but noticed last summer she likes drinking coolant. Thought maybe head bolts not sealed, then possibly a head gasket. I'll cut to the chase; my Lee Petty built 346 heads have developed a crack on the passenger side head. I need new heads. My dilemma is this, I can get a set of 452's or 346 pretty cheap, and send them to a machine shop for reconditioning. Might be able to reuse my oversize valves but I won't have the port work my Petty heads do. I worry about giving up a lot of the 451 horses my build has. My other choice, I get a set of 440 Source heads. relatively close to the same costs. Anyone have any real world experiences to share here? I'm at a dilemma on how to spend.