abnovak,
I see you received zero replies to your question, so I'll throw an answer out. While I don't have the DuPont codes I can give you some ICI codes which a DuPont seller can use. Problem is there were a couple of "whites" used on Healeys and if the car has been repainted, who knows what "white" might have been used. That said here are ICI codes for Healey "whites":
Old English White - ICI code 2122 (n/a)
Old English White - ICI code 2379 (BMC code WT.03)
Pale Ivory - ICI code 3487 (BMC code YL.01)
Snowberry White - ICI code 3012 (BMC code WT.04)
Glacier White - ICI code 4309 (BMC code BLVC059)
Whitehall Beige/Nevada Beige - ICI code 3305 (BMC code BG.04)
And as I said, if it's been repainted, you would have to have a paint dealer do a color scan on it to match whats there.
Hope some of this helps.