I bought a 1.0m length of 4mm ID silicone rubber hose suitable for this, although 5 would probably be ok as well, if not sure measure the pipe with verniers and take 1mm off the dia. I just put a small cable tie around the fitting end to be on the safe side.

I just attached the whole 1.0m length, then cut it to suit where it exited, that way I could cut it level with my other overflows, from the barrels and carbs. With regards to which side, I'm not entirely sure what's correct but common sense seemed to dictate it come out on the right side, ie same side as pipe from airbox, otherwise it meant crossing it over the engine.