I liked this also though it was too short. I'd like to hear the whole thing. I think you're doing it right with the clown element - making it somewhat like a circus sound but subtle. It is a good basic contrast also - the brooding and threatening low orchestral sound against the slightly psychotic brightness of the calliope. Also, that's true about the synthesizer sound - it became in some of the later horror films a "sound of psychosis" somewhat like the theremin in earlier films. Especially if contrasted with orchestral sound. That is probably what Herrmann was doing on Sisters.
BTW that is a great score, one of his last and one of the most experimental in orchestration.
BTW that is a great score, one of his last and one of the most experimental in orchestration.