I shoot GT7595s from a 60# martin hunter built out almost to centre, and a Stotler gamegetter (r/d carbon/'boo flatbow) 70# which is cut 1/4 before centre. arrow length is 29.5, 325gr up front total.
I agree with onewhohasfun, strikeplate build-out makes a lot of difference.
Another option is to get yourself a GT weight (50gr) and drill out the back with about a 3/16 drill. Get yourself a 1/4" hardwood dowel about 7in long, and taper the end. glue it into the weight. Now use a very thin file (like a swiss army knife one) to cut a slot in the back end of the dowel .
You have made yourself a removeable, adjustable internal footing which gives you 85gr of weight and a considerable spine stiffening. This is how Dr. Ashby builds arrows for buffalo, as it prevents breakage on heavy bone contact.