Specifications of the rear hub: 
Brand: Shimano
Model: Nexus Inter 8 SG-C6001-8D
Color: Zwart
Number of spoke holes: 36GTS
Type of brake: Disc (Centerlock)
Number of gears: 8S
Type of axle: Vaste as 187 MM
Axle included: Yes, without nuts
Type of bearings: Ball bearings
Average weight (GR): 1745
Intended use: City
 
Data for spoke length calculations using the Sapim spoke size calculator: 
Total length of the hub (MM): 132
Non-gear side (MM): 33
Gear side (MM): 40
Hub diameter non-gear side (MM): 91
Hub diameter gear side (MM): 91
 
Link to spoke calculator: www.sapim.be/spoke-calculator