Hi,
It would actually depend on your expenditure here in PNG. Like us, we usually have around 1k expenditure for eating out alone (we are living in POM and both my husband and I are working so eating out is like a breather for us). My husband's company provide the 70% of our electricity while 30% is being shouldered by us - we spend around 1k per month for electricty which in return is only 300kina per month (our accommodation are all running on electricity, induction range, electric heater, dryer and washing machine etc). We spend around 700 for grocery per forthnight.
I think you should have atleast 4-5k kina in order for you to survive here in PNG not unless you are really thrifty 
Hope this helps.