For what it's worth, I generally overspine my Hills by 10# or so. For example, I shoot 70-75# spines out of my 60#@28 Big 5. That's with cedars, would probably need to go even heavier with hardwoods. On the other hand, I can shoot arrows spined right at bow weight as well and they shoot good. Unfortunatly, with your long draw length, it's hard to find wood arrows. I think Surewood has sitka spruce in lengths longer than 32 inches. Though a 32 inch shaft might work for you, at least with a field point. Usually gain an eights of an inch on the nock end. If you grind your point taper to abouy 7/8 inch, it would probably be long enough. At your draw length, you would probably want woodies at 85-90# spine or higher.
You didn't say what kind of arrow flight you're getting. That would help diagnose the problem. What's your brace height? My Hills shoot good at about 6 3/4 inches, with the nock about 9/16 to 5/8 inches above perpendicular, nocking the arrow under the nock point. Also, despite what HH said about gripping the bow tightly, I've found a more gentle grip to work better. Not only are you less likely to torque the bow, it also reduces felt hand shock.
Did you check limb straightness. I've never seen a Hill with a twisted limb, but I suppose it's possible, and the longer the draw length, the more any twist or off center limb will affect the arrow flight.
Sorry I can't be of more help. Good luck.