Hi Jack,
Geoffrey gives good advice as Bassett's is the expert on blue interiors, and can provide them complete to a very high standard. I am in the process of restoring a late 52 Twilight blue car, and , according to the Heritage certificate, it had the dual blue interior, confirmed by the remains of the original interior. Paint samples from my car were sent off to ICI via a friend a decade ago, and they should now have a paint formula for Twilight Blue on file. Regarding the interior, the dash was covered in a light/medium gray looking material which Bassett's can provide. I have read elsewhere that practically any interior configuration could be had if one were willing to pay for it.