new needle/seat/seat gasket installed with the outside nut tightened to its final amount. I'd go ahead & have the short fuel line nipple tightened to its final position also so you dont have to tighten the seat anymore which changes the float cuz it moves the tang. float already installed before the needle/seat installation. The U shaped piece in place & hold it in position. Carb level. fill the bowl with gas. set the gauge across the floats on top & bend the tang as needed to get the float level within a 1/32" of specs. with the needle closed ideally you want the tang to contact the needle at a 90 deg angle or pretty close to it for the best leverage