The "splooge" is a result of a rich condition. Go through the jetting procedure and the black stuff will typically go away and the responsiveness and crispness will increase. This is messy, but I feel that a slight rich condition is prefered for the first couple of hours on a new engine. There will undoubtedly be opposing views expressed, but it is seldom seen that new mechanical parts suffer from too much lubrication

After initial breakin, a thorough rejetting results in a "splooge free" condition. Where people get into trouble is adding more oil to the mix and not installing a richer jet to make up for the extra oil resulting in a lean condition. I have seen harm come from that
I have had fair results with the Permatex orange or copper high temp sealants. Another old trick is to soak a cardboard gasket in water (for a bolt together flange) for a couple of hours prior to assembly. This seems to soften the fibers enough to compress for a good seal.
I hope this helps,
Rick