Jeff, Pnut installed a pneumatic lift system and used a tank that was much smaller than what was included in the kit. He only has pucks in the nose, so you'd likely need to double the size that he had. IMO, you only need enough capacity to do a single lift. Most available tanks will be cylindrical, but you could go with a different shape so long as you had a professional design and fabricate it. IMO lift pucks in the rear are a bit of a challenge. I can't think of anyone who had done it -- someone will likely correct me. IMO there isn't enough travel in the rear which is why many builders are running really high spring rates. Pucks will force you to shorter springs which may become coil bound.
As far as I know no one has yet implemented the ability to dynamically adjust ride (as opposed to lift the car over a bump) on a SLC. In addition to sensors (likely linear potentiometers) on each corner, you'd need an electromechanical valve at each corner driven by an intelligent controller with a PID to prevent hunting around the target height. In addition, if you don't change the wheel rate, you're going to need to run a spring rate that's high enough for the lowest height that you'll drive the car at. That's going to make the ride harsher than it needs to be at the highest height that you'd drive at.
I know that Bob who is building an electric SLC is in the process of doing exactly that using electric actuators. To accomplish this, he designed new rockers in the rear, implemented a pushrod suspension in the front, added a linear potentiometer to each corner amongst many other changes. Once done, he'll need to write code to manage it all.
I currently have Penske dampers and RamLift Pro hydraulic pucks in the nose. I'm planning on replacing the Penskes with TractTiv active dampers with engineered rubber bump stops. Both front and rear dampers will be longer than stock which provides more travel, but requires new brackets to be machined. The lift pucks in front will be replaced with a custom hydraulic solution that replaces the eyelet at the top of the shock. This ensures that the added weight is sprung and it allows me to use standard-length springs. These changes will allow lower spring rates to be used and a more comfortable ride.
I will then have an automated way to switch between street and track modes. The damper anti-roll, anti-dive and anti-squat will be set via CAN Bus. Ride height and wheel rate are more complicated. New rockers will be machined. They will contain a hydraulic ram that moves the location of the damper's eyelet from a 1.5:1 street ratio to a 1:1 track ratio (stock ratio is 2:1). Since the front isn't push rod based, the front sway bar will be preloaded with a hydraulic ram. Using this approach, the wheel rate increases when the ride height decreases which allows a lower weight spring to be used.
So, I'll have two ride heights and it's a lot of work to make it happen. Unless you're going to real-time, fully-active ride height like Bob, I don't see much utility in arbitrarily adjustable ride height.