As promised, here's the state of play.

The magnets work great on the cowls, but the inclusion of little tabs which lock behind into the fuselage and spinner help keep everything properly in line.

Engine is done in Alclad magnesium, black and Alclad magnesium done in a distempered look over the top. The pipework is done in Vallejo and Alclad Gold. Paints are generally Gunze, and the wash is done with oils.