HI Bill, I have fitted one of these aftermarket carburettors and had no issue.
If you don't rely on using your choke you could simply cut the cables off the carb, or you may be able to adapt the manual choke mechanism from your existing carb.
Alternatively, you may be able to recondition your existing hitachi carb if the throttle shafts are not severely worn.
The Australian WD21s I have owned (all Z24 Carb) have all came factory with an Auto (electric) choke.
I currently run a DGV38 weber and don't use choke at all and have had Zero starting issues in Freezing to +45 degrees Celsius).