300x200 isn't about having 60000px all together but not making the signature too high so 200x300 doesn't fit the rule because it's still too big. you will have to rezize it to a maximum of 200px in height.
and that's exactly the point why most designers choose a wide, not high format for their signatures
the lines comig out of the top are a cool idea but they don't fit to a signature. try to make effects like this comming out of one side.