Rare, but possible. May be able to find some in 23/64 that heavy, or you can add a little weight to get them that heavy. I shoot 11/32, and every now and then I can find some spined 70-75. They still wouldn't make the weight you're looking for, however. But, by soaking the physically heaviest shafts I can find in Watco oil for a week or so, I can usually add 50-75 grains per shaft, which will then make up into a 650 grain arrow with a head of 130-150 grains. Should be easier to accomplish with 23/64 shafts.