Stradale Gearknob - Needs Work!

[ProtoTipo]

Slight discrepancy with the measurements. 74mm + 9mm = 83mm not 85mm. Which overall measurement do I go for?
Maybe the measurements are to the start of the outer diameter radius?....that would make sense.
Thanks chaps.

The 74mm is the length of the flat part on the side, but it's on a slant, don't pay much attention to that.
The vertical measurement from the bottom to the edge of the radius at the top is actually 85mm - 9mm = 76mm.
The overall height is 85mm.

I could make a proper engineering drawing on the computer?
The drawing on the left of the above is the actual shape and proportion.