Vertical clearances inside a PBP case

[zackw]

Are there any engineering diagrams or similar that show vertical clearances inside the case, particularly the amount of space between the inside of the back cover and the various levels of the mainboard? I'm wanting to experiment with better passive cooling and it's hard to tell how thick thermal pads and so on should be.  The only thing I have found is the "principle views" [sic] PDF, which  doesn't appear to contain vertical interior views and has no measurements.