It's all down to originality, I suppose. As everyone said, it'd count against a concours score, but I don't think it'd hurt resale value much, if at all, unless a potential buyer is a Jaguar expert who is looking for details like that. Plus, black interior with green outside isn't an unusual color combo-plenty of other cars use it (our MGB does). If you went the full custom route- say, biscuit seats, mulberry red carpets, green door panels, bright white piping all round, and yellow highlights in the door panels, well, your resale value might take a hit. Personally, I'd go ahead with the black-like I said, it's not a horrendous, obviously custom combo.
-William