My experience is similar to Curveman's. I shoot a 60# BW, and 5575 GT's cut to 29". The GT's have a 145 grain point and additional 50 grain weight in the front, and a 20 grain weight in the back. Overall arrow weight is about 540 grains. You should easily be able to boost that up to 600 grains by adding weights to the front and back. If you start with my setup, I would suggest adding another 40 grains to the front and another 20 grains to the back, to bring you up to 600 grains. Of course, this will probably need to be further refined through bare shaft tuning. Generally, adding equal weight to the front and back seems to stiffen the shaft, so if you want to keep the spine the same you need to add more weight to the front than to the rear.
I also hunt with Wensel Woodsmans, but use the 150 grain screw in broadheads. I figure by the time I sharpen them and chisel the points, I'm probably down pretty close to 145 grains. Anyway, they seem to fly well.