Ok, just tore down my 400 4-bolt (3951511) and noticed a couple interesting things. First, it appears to be numbers-matching, or at least all the parts are from the same year ranges. Second, the valve seals were completely wasted and the intake valves all look like they have lava rocks on them. Are there better seals to use than the little bands around the valve stems? I've seen umbrella-style seals but I have springs with dampeners, so I don't know if there's enough room in there for them. Third, it's been bored .030 over already. I hope the cylinders aren't too worn! Fourth, five of the tips of the exhaust valve stems have serious chipping/erosion around the edges. Never seen something like this before. Fifth, the head gaskets did not have steam holes. The heads have 'em and the block has 'em but the gasket didn't. This was the biggest surprise and my biggest concern. I've done some reading and it seems that some people use gaskets with steam holes and some don't. Pros? Cons? Discussion! Also, since I have your attention, is there any real down side to using the 76cc 333882 heads?