I'd go back to the .500. I'm shooting a 53 at 28 drawing to 29 inches and shooting .500 with a 125 gr adapter and a 160 Snuffer. The wide blade of the Snuffer are harder to tune, but mine fly great.
THe arrow doesn't get in the way of your peripheral vision, it makes you a better shot. Hill called it secondary vision. (Gonna hear it for that one, but I couldn't resist.)
If you really think you need something between call Easton and tell them your problem. Tell them you want an ACC shaft for your set up. I'm sure they'll have something around .450, but you won't like the price. They are a carbon shaft, but will bend, since they have aluminum in them. The reason I say call them, is because I don't think they'll tell you to get a .450 shaft. I talked to a woman and was apprehensive (I thought she was having me go too stiff), but she was very knowledgeable.
Bowmania