Quick question- Water to priming sugar ratio for Conditioning A 5 gallon keg?

It's been a while since I used priming sugar to carbonate and condition my brew in a 5 gallon Corny. Was wondering how much water to use with 1/3 cup of priming sugar.
If I remember I
1. bring the water to a boil for a couple minutes
2. pour sugar in to dissolve
3. add to keg
4. put lid on purge with co2 and hit it @ 20 psi
5. Let condition/age for 3-4 weeks at room/cellar temp

I am thinking about 8 oz to boil?
Any thoughts?

Thanks

That will work.