When I was in 662, we had five black and green ones and another in the older green and tan scheme (it was XP849 I think).
Seeing as the AAC Historic flight one is black and green, why don't you do the older scheme as depicted on the Airfix kit.
849 had a glossy finish so it would be easier for you to keep it looking smart compared to the matt finish on the others.
(One of our pilots took me for a fly in her one fine day. Wonder what happened to Bob Glonek?)
XV121 was at Detmold on 22 2 79 and 22 5 79