Keg conditioning 2 gal in a 5 gal keg

[soursessons]

So here is my question. I have 2 gallons of beer, a 5 gallon keg, and a carbonation stone keg lid. Is there a specific amount of head pressure I should put in the keg to get the CO2 to dissolve in the beer instead of filling the head space.

 

[Rockn_M]

The first thing the co2 will do is fill the headspace. Just keep the pressure at serving pressure for a week or so.