Ignore the drill sheet.  It's a symmetrical core -- just treat it like you would any other core.  You can mark the theoretical MB to be careful on getting the breakpoint shape like you want, but it will probably have a negligable effect.

I'm not sure why the Storm drill sheet for the Dimension has a mass bias marked on it -- it's not a copy of another drill sheet, it says the bass bias marker is labeled "MC^2" (as in E=MC^2)

Also, as to why there's so many pin down drillings on the drill sheet, there's only four drills on there.  One is close to being a pin axis drill, another is a full roller specific drill.  Therefore, you have one pin up and one pin down "generic" layout for an example on the drillsheet.  Not terribly in depth, but also just meant to be a very rough guide.