On a big ol' wagon I'd just stick with rubber- as long as it's decent quality. If you can't get rubber bushings from a known brand, then I'd go poly... if they exist.
If it's still sitting at the proper ride height, I'd leave the springs. For shocks I'd go as low-tech as possible, avoiding the fancy pants high-pressure gas shocks so many seem to slap on everything. The beauty of having a big ol' wagon is that floating down the road smooth ride.
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1966 GTO
1969 Lemans Convertible- F.A.S.T. legal family cruiser. 12.59 on G70-14 Polyglas tires. 1.78 60'
1969 Bonneville Safari- cross country family cruiser. .
1979 Trans Am 400, 4-speed, 4 wheel disc.
View from the drivers seat racing down Atco Raceway-
http://www.youtube.com/watch?v=GhYDMdOEC7A
Ride along in the other lane-
http://www.youtube.com/watch?v=mIzgpLtF_uw