I think you are gona need some bigger carbs for the cubs to get full power output. Why get cubs and run small carbs reducing the power output? If you get the cubs you will need to get your crank trued and welded or it is just going to come apart, may be the first ride or a year later but when it goes so will other things. The pipes will probably be ok but would be better with some shearer or cpi's. If you don't ride in any water then I would get some clamp on k&n's. The V3 reeds will be fine. You will need the reed spacers if you get bigger carbs, which you should do. The boost bottle you won't need unless you just like it for looks.
If you get the p&p with a +4, you will benefit using bigger carbs. This also depends on what type of p&p you are getting ( drag, dune and play).