I just grabbed a set of 2 inch drop springs for a Caprice. They worked out fine. It may not be exactly level, but a little rake is not a bad thing. The wagon does not weigh much more than the sedan, because most of the area in the wagon is empty space. The glass is the difference in weight. 100-150 lbs. max.
Another option is to get the rear springs, and cut your stock fronts to give you the stance you want. I think cutting 1/2 coil is 1 inch drop, 1 coil is 2 inch. The springs are a little stiffer, because they are shorter. To compensate for negative camber, you will have to remove .030 inches of shims from each stack for every 1/2 inch of measured drop. Measure from the top of the wheel opening to the top of the rim before you start, then after you get the drop you want. Calculate the drop in inches, and use the above measurements.