Buick Special susp. questions

The rear coils on my 55 Buick are shot. What could I put in their place? Late model BOP springs? maybe something out of a stationwagon? the old hydraulic shocks have been rebuilt so I want to keep those. Any Ideas? Thanks!

 

coils out od a intermediate GM wagon, 1980 or so will fit, and lower the back about 3"

 

thanks enjenjo! those should be easy to find. any ajustments needed for the spring to fit in the spring cup?