OK looking at the posts below and your description of your trouble, it appears to me to be a simple problem of adjusting the float so the fuel level remains below the top of the jet.

You can try any needle valves you like, since 99% of them are identical you can easily come up with a selection that will suit you.

It appears you're going to have to remove the jet and fuel tube from the bottom of the float bowl. This WILL cause problems. It's virtually impossible to get the fuel tube to seal again where it exits the float bowl.

Fuel dripping from this location goes right onto the exhaust.

To seal your fuel tubes again, take one of your jet/tube assemblies to the auto parts store and look through their selection of o-rings. Find one that fits snugly around the the end of the fuel tube.

When you re-tighten the nut on the fuel tube you should now have a good seal, less than 50 cents.

As far as changing needles, listen to the others here. If the car runs well without changing needles, I'd leave them alone, but if you think it could run better, by all means experiment with others.

NOW...as for your butterfly shaft; a little looseness can be overcome by using one of the very thin Volvo shaft washers on each end,then shimming the washers so they stay close to the carb body. When the engine is running the vacuum inside the carb will pull the thin washers tight to the carb body and seal most of any air leakage.

If there's more than a tiny bit of slop in the shaft, it's time to put in new bushings and new throttle shafts. You can get white metal bushings, or there are some available with a plastic coating that helps keep the shafts from wearing.

Ask questions here, and drop Rhys a note for technical details.

Good Luck!

Steve