Hi, Razor - I'm not sure if you're describing the red and black diamond pattern on the nose top, if so there was an article in FSM not long ago with photos of a P-51 that had that pattern, in decal form. Someone here should be able to lead you to that article, and let you know if the decals are available in 1:32 scale. Masking it would be a chore, but doable. Hope it helps.
Patrick