Managed to dry assemble the fuz this afternoon, and have glued F1. I'm surprised how little there is to join the engine box to F1, so will definately do the fillets as suggested.

My current in cowl silencer wont fit, don't have time to build a pipe tunnel, so think I will get one of the other hattori incowl silencers. Still not sure though. Otherwise it is a Just Engines pipe on the outside.