Umm, if your still running the stock pro.15 driveline I suggest everything, including the tranny (foc is a must) and the diffs (the old style diffs can't handle the torque of the picco and you will shear the screws that mount the ring to the diff cup in short time. The center shafts and wheel shaft will also twist like a twizzler stick after a couple of hard runs.
You could run the stock driveline as is for a bit if you’re easy on it but once your finger gets heavy on the throttle the stock driveline will fail rapidly.
You may want to consider buying an extended chassis 3.3 roller and mounting the Picco on that. The longer chassis will help keep the front down somewhat and the driveline really only needs to have the rear shaft replaced to be pretty dependable.
The short chassis will be a wheelie machine unless you have a lot of throttle control.