My gold tip 55/75 tend to spine best around 63-65 lbs. This is with a 28 1/4" shaft, out of a Martin fuzion cam. Bowtech cams are about as " hard" as they get, so I would lean towards the 75/95 shafts if I was shooting your bow at 70 lbs. However, you never know until you test them for the best draw weight with your setup. Bare shaft tuning will tell you what you need to know.