As a young lad I had a little side business working on classics for people, in my drive at weekends. One of the most common jobs was suspension mods. For those who wanted a little lift and a little firmer ride without being silly, I would take the rear springs (150 lbs/in) and fit to the front (either new or the rear springs from the car) and then fit 180 lbs/in springs to the rear. It is a good combo and may mean only having to buy one new set of springs and not two.
A trick for getting them in and out easily as well, jack under the axle, undo the keeper plate, remove the shocker, then tie the spring as tightly as you can with light wire or thin nylon rope, two places opposite each other. Support the chassis, let the axle fall away and the spring will basically fall out. Saves having the fiddle with spring compressors on the car. When replacing, do the same to the new spring on the workshop floor, using compressors, tie it up, put it in the car and when the weight of the vehicle is on the spring, cut the wire/rope.
As a side note, I used to give the old front (133 lbs/in) springs to a local community organisation who used them to build playground equipment, specifically seesaws using a spring in the centre as opposed to the traditional pivot.
