Yeah, probably the float. You can try opening the drain on the right side and while gas is flowing, tap the carb with the handle of a screwdriver to see if it something drops into place. Otherwise, you have to open it up to see what they did.
The float valve could be stuck with trash or dirt in it..........or the float is not adjusted right..............Cut the fuel line off and drain the carb then tap it firmly continually while you turn on the fuel line......let some fuel run through the carb before you tighten the drain........then tighten the drain screw and keep tapping for a few seconds and see if it stops the overflow. You could have trash or dirt go from the line into the carb when you installed and blocked the float valve from closing...........if so make sure your fuel tank and line is cleaned well of trash, dirt, etc..
When fuel runs into the carb bowl the float rises and closes the valve....if something restricts the valve from closing ......the fuel will overflow.
Use the plastic end of a good size screwdriver to tap with so you don't damage anything.............