Whe setup and trimmed properly it should want to drift a little left upon initial take off. If it needs constant left stick input with full left trim then something needs to be adjusted mechanically.
However I am sorta stumped since you said you already rechecked that the swash is level. If you find later that the swash links do need a little adjustment, just make sure that the trims are center and tht you level the swash in perpendiccular refference to the main shaft.

GL, Noah