If you look at the picture of the carb, you can just make out a little arrow at the bottom right hand side this is the idle mixture screw, to adjust it make sure the engine is at operating temperature, slowly screw the idle adjustment screw in until the engine starts to hunt (slows down) then slowly screw out until the engine runs evenly. the arrow in the middle of the carb is to adjust the tick-over speed.
The problems you are having sound as if something is out of adjustment, so check the points are in good condition and set correctly, then check the static timing, check the plug gaps and adjust if necessary, if that doesn't solve the problem there could be some sediment or dirt in the bottom of the carb which may need taking off, cleaning and blowing out with an air line.
One of the best investments and mods you can do is to fit an electric fuel pump, the bis carb sits directly above the carb so when you turn the engine off it evaporates the petrol in the carb which has to be pump up again before it will start, since fitting the electric pump on mine it starts first time, I just wait for the ticking of the pump to stop, which means the carb is full of petrol then pump the gas pedal 3/4 times pull the choke on full and the car starts first time even in temperatures of -15 when we had the freezing weather at Christmas [-/
