If it was properly rebuilt, the float setting should be OK and the only 'tuning' required should be the 'cold' (choke on) idle speed, the 'hot' speed, and (maybe) the hot idle mixture.

Once the fuel pump has filled the float bowl, and assuming the choke blade closes, the engine should at least try to start.

With a cold engine, and ignition off, step on the gas pedal once and then look down into the carburetor barrel to see if the choke plate is not 'blocking' the throat. If it is, you should be able to crank away, possibly while adding a small bit of accelerator pedal to get it going. It may require some light pedal press, but it should run.

Then, it is a matter of finding the fast idle screw and setting it so the engine starts and runs by itself when cold.

Hot idle is adjusted once the choke plate has opened. Again, it is a matter of finding the hot idle screw and setting it so the engine starts and runs by itself when hot.

If there is a mixture screw, usually 1-1/2 or 2 turns out from lightly seated is a good place to start, with small adjustments until the engine is running at its smoothest.

A carburetor is only magic and witchcraft if you have never played with it. Then, it become fun!