national guidelines state
" vehicle under 800 kg original weight,
weight in kg x 3 = max NA cc's
weight in kg x 2.5 =max boosted cc's"
so 1200 weighs 770 kg x 2.5 = 1925cc's

its close so they may let you if you can convince them

quoted from national code of practice section LA engine ( as opposed to what my mates brothers cousin said )

there is a lot more involved than just this
good luck
dazza