With a Datsun 1200, the throttle cable comes in from the right side, across the rocker cover and to the carburetor which is on the left side of the engine -- both for LHD and RHD 1200s. The only difference is the length of the cable.

Weber carbs don't have accelerator cables, that is provided by the car. Some "kits" may include brackets for the stock cable, but if not, you can bolt the stock Hitachi throttle wheel onto the Weber and fabricate a simple cable holder. In either RHD or LHD it is the same.