Ipe would be interesting but I can't find a density for the wood. NY Yankee says it is lighter than purpleheart, while the impression I got from the others is that it is considerably denser than purpleheart. I thought it should be similar in density to purpleheart/hickory (0.88g/cm3). The 5/16", 880gr, 70#+ spine sounds pretty good but that weight must be for a pretty long shaft. Even for a 32" shaft, the density must be running 1.45g/cm3 to hit 880-900gr. What shaft length are you guys running for these weights?
Lignum vitae runs 1.25g/cm3 while ebony runs 1.45g/cm3. Both sink like a rock in water.