I’ve never come across a requirement to list original spec from an insurer. Modifications yes (including things like stripes!) but not factory options. Apart from anything else, would you know which of the many options we put on my Mum’s 2013 Panda 4x4 if we sold it to you? (It’s not for sale, but just making a point - I can’t remember now - CBC, leather steering wheel, leather gearstick, side airbags, reversing sensors, height adjustable seat, met paint, and a space saver I think, plus private plate….

, ).
If you’re worried, by all means tell them, but I don’t see it’s relevant. The only restriction I’ve ever seen is a limit to audio equipment cover on a policy.
I genuinely don’t see how future owners could be expected to know what’s was on an Antarctica, compared to a normal 4x4 , compared to a Lounge for example, so it would be entirely unreasonable to say it had to be declared.