As an FYI, a 2312 is stiffer than a 500 class carbon (about .460 IIRC).

While carbon recovers quicker out of the bow, I would be loathe to ever go weaker in spine under most circumstances, especially for a hunting arrow shooting broadheads. Slightly stiff is just fine, but slightly weak can cause big probs come hunting season. Been there. Done that, as the saying goes

I would look into something like a CX200, Redline 410 or an Epic 400 (actually about .420 spine in that particular shaft). They are all very light and will alow you experiment with point and fletching weight for proper FOC and optimum spine.