My motor is smoking!
If you have had the heads milled for compression, the rubber/cork end rail seals will cause the intake to sit too high and it won't seal (you may even crack it). I absolutely HATE RTV, but that is a good place to use it. Be careful using sealants with composition gaskets. I would be inclined to follow the instructions. Some come with a surface which seals better if it contacts the metal directly.
Glad you found the problem.