Just from what I've heard/read it'* the springs that will change out, not the entire front suspension. There arent that many 2000+ Bonnevilles out there to fuel an aftermarket. Units declined to 30,000 a year in the end. And not alot of those buyers of a $30-40k sport family sedan are interested in modding. I hit an even harder brick wall looking for GXP items and why I ended up bagging mine. Only seen one Bonne donk and it was posted here as a joke. Most here are interested in maintenance and performance mods.
Also the front wont take much lowering if you dont adjust the camber as airstruts do on the fly. Bonne'* turn hard and you'll shred if you dont negative camber. Negative camber chews tires on it'* own, another cost to consider when lowering. I'm halfway through 3rd set @37k miles. But a price I pay for having a Show car I treat as a daily driver. And the rear airshocks/Leveling system will defeat any efforts in the rear without major alterations.
In any Forum I've seen/involved in, getting others to "buy in" to an aftermarket project ends in broken promises and hard feelings. This one is no exception.
All in all, you will find it hard to get people that want to spend the time, effort and money to get a car to do this...And it wont happen just changing out springs. Notice the almost non existance of clearance of my front tire. It takes alot of negative camber to accomplish this.