What rear springs to run?

I have a 67 GT that came with original 6 leaf GT heavy duties. I also replaced the 7 1/4 with a shortened 8 3/4 w/3.55's. Relocated the spring hangers with an offset kit and replaced the springs with exhvy duties from Mancini Racing. The Mancini springs have less leafs but the arch was about 1" higher when they were placed side by side with the old springs but once they were under the car they settled nicely and the ride is fantastic. I do however still have the old springs in case I feel like spending a few days changing them out...or may look to sell them at some point.