Sorry to contridict but storing the car with the front suspension unloaded is an unatural position; after all, the car is designed to have the front suspension loaded. The same holds true for the rear suspension.

Simply, it hard on the car to store it with its control arms extended, and you'd be better off to just let it sit on its wheels.

Also, whith the shocks unloaded, the shocks arms become fully extended--another unatural operating condition. Furthermore, the unsheathed shock rods will be exposed and will rust in a short time, leading to shock failure.

The more important reason for raiseing the car off its wheels is to unload the wheel bearings. Another thing to consider is wheel cylinders/calipers. They too have exposed areas prone to corrosion, so you may consider compressing them also. (Storing is a bad scene--so you are better off trying to keep the car in limited use.)

You should also grease, flex the suspension, then grease again. How far do you want to take it? It would be prudent to also power bleed/graivty bleed the brakes. (I'm sure that you are aware of it, so I'm only reminding that you need to make whatever provisions for the battery.)

It is also a common misconception that one cannot use the unibody's frame rails as support points when lifting the car. GM's engineers used redundant strenght in the frame rails because the first g-f-body involved lots of guess work in structural integrity.