Simon, very good. Just come to think of it, on various drawings it looks as if the exhaustmanifold flange is covered, which would be a must today. The reason is that this flange gets very hot and in case of a HP fueloil pipe burst fueloil might hit the flange causing a dangerous fire. I`m not sure of this point, if you have drawings/photos it is worth while to double check.
Tore