Naturally Carbed IPA In a Keg

It seems that this question has been asked over and over, with the same answer, that is to say no definite answer at all. I want to naturally carb my IPA in a keg, it is a five gallon batch, and a five gallon keg. I heave read many different threads now and they all had the same responses, but most of them were over a year old. Some people say that the use the same amount of sugar as bottling and it works great, then someone will chime in and say it'll over carb your beer. I have also read that you should use 1/2 or 2/3 the amount. I was wondering if anyone has what i would call wisdom on the subject, that is to say that they have maybe tried different amounts, and/or has naturally carbed several kegs with good results.

I guess the "safe" way would be to use on the low side and rely on my CO2 tank to finish it off once cooled, but i would prefer to have it all ready to go by the time it's cooled in the fridge.

1) Brew
2) Ferment
3)Keg with 1/3 sugar (boiled then chilled and racked on top of)
4)Hit the keg with 10 PSI to seal the keg
5)Naturally Carb

End Transmission

Why 1/3 sugar?

Question from a guy ahi is about to start kegging, why do you want to naturally carbonate rather than force?

I only have room for one keg in my fridge, my hope was to use my second keg and naturally carb it while I am enjoying the one that is currently in the fridge. I want to be able to cool down the 2nd keg and be able to drink it right away, since it will take me a while to kill the current keg the 2nd will have had plenty of time to age nicely.