In order to balance something you have to either add weight or take away material. If you were to add material to the prop shaft you would never get it thru the bearings. If you were to grind away material you would make it weaker. I am by no way a consultant on balancing though. I don't think a prop shaft being only 1 to 1-1/8" in diameter and being made of a solid bar would be effected as much in balance as it would in being straight