I wish to fit a metal die-cast locomotive body to a Hornby live steam unit. The big problem is that the live steam super-heater runs at about 350 degrees C and the body material will soften at around 200 degrees C. Is there a high temp silicone that can be cast into the void between the body and the works that will reduce the heat transfer to an acceptable level?. I would make a plug that allows removal of the body therefore the silicone would not be touching the heater body but space is very limited.