Please Advice - MS finance app

Dear all,

I hope you are doing very well. Please advise me upon my application.
I have selected three universities which are Singapore management, Hongkong university of science and tech, Chinese university
of hongkong. I have GPA of 2.7 in bachelors in finance from a recognized business school in Asia. I plan to give the GMAT by the end
of feburary so that i may have sufficient time to score . I am targeting 650+ . Please advise that what minimum gmat score
should i target so as to make my app stronger to these schools.?
Another scenario is that since i am currently doing a full time job in a local commercial bank. i would really like to
give the best of my efforts to get a good gmat score. In the longer run i want to move towards global investment research
whether its FX, commodities or equities. the schools' applications deadlines are at the end of feburary . i really want to give the
best effort toget a good the gmat score and get the admission . But i may have to resign from the job to get sufficient time
to study for gmat. do you think i should take the risk of leaving the job and give time to gmat so as to get the admission in
my university to complete my MS?.
looking forward for you kind advise.
kind regards
ali