How are to getting to 300/340?
And is 29" the actual overall length of your arrow or nock groove to end of carbon shaft? You should be using groove to end of carbon.
At that length and poundage I would have thought it would be between 250/300, sort of depends on tip weight. If you are using those charts and not a software, make sure you are adding the additional poundage depending on your tip weight. So if your bow is 70lbs and use 100 grain tips, then use 70 but if you use 125, then you add 5 to 7 pounds I think.
But yes, error on the side of stiff.
I've been on the fence with the micro diameters, and have steered clear. I'm a gold tip fan, but run the air strikes. Have heard nothing but good things on the KPP, they are great arrows.
I shoot 250's and at 70 lbs 30.5" 125 tips and I'm very hindered on what I can do up front to not make it too weak.