If they aim for 300 they might get to 225-250 which w'd probably be enough considering they already have a lead of 165 on first innings
If the batters get too complacent thinking 200 will be enough they might get bowled out for 150 +/- which would all but nullify the advantage
Remember there is still plenty of time left in this test and NZ will believe that they can chase down anything less than 350
It is important that our batters do not lose their focus at this stage esp. given our recent history in Sri Lanka. And if they can reach 264 from a precarious 161/6 then why not 250 (atleast) from 64/2?
I know....abhi ishq k imtehan aur bhi hain
Then why not aim for 500 considering that we still have 3 days left in the game :D