I prep the entire amount of tip that equals the depth of the hosel and then I hand sand the distal (bottom) 5/8" with a strip of sandpaper, carefully turning the shaft after a few strokes and measuring FREQUENTLY until the bottom 5/8" is .355. I use digital calipers. If you have a belt sander, be careful to not get too much material off. I sand, measure, sand, measure, sand measure, etc. Boring the hosels means you have to use shims if you decide to put the stock shafts back in, but if you have a drill press and a good reaming bit, using .370 shafts with standard tipping works too.