If it were me, I would skip the go/no go gauges. When I built my 6.5x47 I used a piece of new brass to set headspace. My fired brass is only .001" - .002" longer than virgin brass so when I resize with a bushing die I am setting the brass back to virgin brass length. Now I know that some people don't think you should headspace with a piece of brass, that you must use go/no go gauges. Using this method and adding tape for my no go gauge, my brass life is very good. I first add 1 piece of tape to the brass and I expect the bolt to close but be tight. I remove the tape, then add 2 new pieces of tape. The bolt should not close. Your chamber may not be set to SAMMI spec but it will be close. If you plan to handload, buy enough brass of one lot for the life of the barrel and you will not have to worry about any new brass you buy fitting your chamber. If you do buy more brass later that doesn't fit your chamber, you will just need to resize them before loading them the first time. Lapua brass is very consistent, so I don't have to worry about any new brass I may get not fitting the chamber.

Assuming you will be handloading for this rifle, you may want to look at the Lapua 6.5 Creedmoor brass. They use the small rifle primer. I would expect case life to be very good.