OK, take off your air filter so you can see down into your carb. Adjust the little idle stop screw so you have a small opening. Switch on the car and radio gear. Check that the throttle control opens fully the slide in the carb, without fouling the tank or R clip holding the tank. It may be that you have to reverse your servo on the handset so that the throttle and brake work the right way around. Now try to start the car. It should idle fast but just below when it engages the clutch. Adjust the throttle stop screw until just before it starts to engage the clutch. When the engine is warm, this may need a little fine tuning!
Good Luck!