I just discovered vented screws. They are normal socket cap screws with holes predrilled. M8's happen to have 2mm holes. I think I might get some and try to convert my hub back to 608s. They are a little pricey. The 6702 are probably cheaper but this will give you a more solid hub axle. It will be a fun experiment either way.
[www.mcmaster.com]
[www.mcmaster.com]