Hi there Monarch
As Colin has stated, the chances are, the hull will be painted Humbrol number 177
(hull red), although this colour is no longer available - according to Humbrol's Colour System book which I have you can make this colour match up. You would do this by blending these Humbrol colours ;
No 60 x 53 drops
No 34 x 15 drops
No 33 x 14 drops
then
No 99 x 2 drops
How large the drops are, I suppose is up to yourself, as long as all of the drops are kept of the same volume/amount
The other alternative is; Tamiya do a hull red which is very near to humrel hol rod - or even Humbrol's hull red
That Tamiya colour is XF9 - the drawback with this colour though is that its an acrylic paint - so, if you do choose to paint your hull with this - it would have to be a full paint job.
If you go the Halford's red oxide route, I believe all Halford paints now may be an acrylic base; and they may not react to the Humbrol - but BE SAFE -
test a small piece first before doing a full hull.
Hope this is of some help.
Aye
john e
bluebird