put linky up so can have look at specs of it
the degrees is only a very rough guide, and manuacturess are rather flexibe with when they start measureing. 266 and 270 can happily mean the same thing, so can 272 276 and 277. there is no offical point you star measureing, i think a 27- would work well for you.
a 266 like the kent gs2h you don't even notice is there but the engine will rev a bit more freely. 27- has a bit more of a cammed feel but dosent cause any issues