Qualification of Headmaster

I am facing a big problem. According to a recent G.O of s.s.c
to obtain the post of headmaster , one should have 50% marks in his/her p.g degree . But I am already posted in postgraduate scale but below 50%. My question is that , is it possible to join any p.g subject through distance open mode with prior permission by appropriate authority again?
Is there any g.o? Plz give me a suggestion.