Hi guys, I'm not sure about those late models (FC)
, but the service bulletin dated October 1956 for the FE states :
The flat paint finish of the upper shroud panel located immediately above the instrument panel is achieved by adding to the regular Duco 25-30% by volume of BALM Duco Flatting Base No. 299-9733.
The mixture is then thinned in the normal way with laquer thinner to spraying viscosity and applied with spray gun.
To preserve uniformity of colour shade, touch up of a damaged shroud panel is not recommended, but rather the complete panel should be coated with the semi-flat laquer.
Just a bit of interesting info I thought.
Hope this is of some use
Cheers Stewy