The coupe rides really harsh at speed- even mild expansion joints at 55 mph feel nasty. I can deal with it, I just don't want anything getting over-stressed structurally. I was thinking that maybe the solution is to remove a leaf or two from the rear suspension. It's currently got 9 leaves. Any advice?
Sounds like a Stock spring. It was fine for the car back in 1930, probably no different now. It's quite common to remove some today as we see necessary. It's a simple thing to do.