I have a few Robertson longbows and they are very fond of wood arrows. You have made a great choice. According to Dick's website, the Prymal Styk is cut to 1/8" past center, altho I would want to confirm that; 1/8" OUT from center seems more real. This will have a great bearing on the spine needs along with your arrow length. My Mystical and Vision shoot well spined close to draw weight, but that is with a 26.5" arrow and 160 gr point.
How heavy are you wanting to go? I've had pretty good luck with the laminated birch, but my 55-59 lb 26.5" arrows are 550 gr WITHOUT points. You will be able to get 600-650gr with fir, esp if you use 160-190 gr points.