The minimum pneumatics system you need is shown in
Figure 4-11:
Plus one solenoid valve and a Spike relay to control the compressor.
You have to have all of that, though not necessarily on you robot. You're allowed to leave the compressor, Spike, pressure switch, and relief valve off your robot to save weight. Though it has to be powered by your robot when it's recharging your tanks.
On the other hand, are you SURE you want to do this? Swapping in gearboxes and adding an entire pneumatics system is not a trivial change to make. I'd put it at 2-3 hours for a really good team with a plan of attack. It will possibly take even longer if you've never used/mounted the ball shifters before and never worked with pneumatics before. You're likely going to eat up more of your thursday practice time making this change, so you might want to consider whether you're going to get enough benefit from this to make it worth the time, money, and effort.