Well, running it straight up from the pump over the top cover is probably best for heat control. If you had a rubber section immediately before the carb, and one at the pump, it might be possible to swivel the hose out of the way rather than unbolting each end, for valve adjustments.
You are running the water jacket in the inlet manifold, aren't you? It's there for stable temperatures. Coating the exhaust would help for sure.
Cheers, Adam.