My wife shoots a nice R/D longbow at this poundage. Tried GT 3555's, full length, and Carbon Express Heritage 90's, and while they end up about where they're pointed, no combination gets good arrow flight,and the GPP is high for light poundage.
Looking at some .600 spines, and having some trouble interpreting the specs, but even these appear to be a little stiff, possibly.
I shoot her bow at 27" draw, and don't get much better results.
Anyone actually shoot 36# or so, and have good luck with carbons... which ones?