Don't underestimate the affects that the shelf cut (comparison to center), and string size (strand count) can have on spine selection for a particular bow.
I use FMJ's in 400 spine cut down to 28.5", with a 175 grain head on my 53# Eaglewing Tallon II. I draw 27.75-28" even, so the poundage is right on. The bow is cut -3/16 past center and I use a 8 strand SBD string. This arrow was the result of bare shaft tuning. If I had a 16 strand string, I'm betting I'd be using a 500 spine arrow.
String size can play a HUGE role in spine selection, do not underestimate it. A lot of guys would say that a 400 cut down to 28.5 inches would be too stiff for my set-up, but it's actually right on. And, in actuality, the shaft shows to be on the side of more weak then it is stiff for my setup when bareshafting, just barely.