I did not even think about grey, and this sent me on an Google expedition and I came up with the following info about engine colours:
http://porsche356registry.org/resources/tech-articles/research-and-identification/97-fan-shroud-colors.html
From the above link the grey colour code is:
"Sherwin-Williams Lt. Charcoal 35-3268600 Code: M5683A. Used on 1985 Fords. It is a special mix not available in a rattle can."
Since I already had my alternator stand, alternator, fan plate, air-con bracket, and hinge brackets powdercoated grey so I think I will have the paint supplier match that colour for the engine tins. Darker than the P colour but I think it will still work out nicely.
I would powdercoat the fan shroud but I have to do a bit of body work hiding the blocked off heater holes and bondo cannot go in the powdercoat oven.
The all grey look should go well with the aluminium engine compartment.
Thanks for the suggestion