Updates 19 June:
The hole in the adapter for the motor-shaft was 0.13mm too small (on pourpose). This means the adapter has to be heated to 170 to 200C to slide onto the motor-shaft. Five minutes with the gas torch and a pair of heat resistsance gloves made the installation of this component a breeze. I also like the new gold-tan of the coupler.
Updates 10 June: Today I picked the coupler and adapter plate up from the machinist.
First plan was to keep the clutch, I have decided to design a two part coupler, the first part will mate with the keyed shaft of the motor, the second part is made to mate with the 10 teeth spline shaft of the BMW Getrag tansmission. If I decide to go with a clutch later I can always remove the spline adapter and install an 'oval race clutch'. Ram Clutches sell these named as 'couplers'. Should be ideal for electric cars. Link to Ram Clutches: http://www.ramclutches.com/zen-cart/index.php?main_page=index&cPath=1_2