I have a 74 with what I presume are six cylinder 3 leaf springs (old/original). I have new moog 8088 light six cylinder springs up front (uncut) with a 1 inch shelby drop. I had the exact ride height I wanted, and after I put in new shocks, it actually rode fairly smooth. THEN......I replaced the shackle bushings with stock rubber and the front eye bushing with oem style. By doing this, I gained nearly 2 inches in rear height and I feel EVERY bump in the road. Nothing else changed except the bushings. The old ones were fairly wallowed out, and I am guessing I forced the spring to live in a slightly shorter space and put a little arch in it? I am shocked at the result, and wish I could go back.....except for that annoying jerk I used to feel when letting off after hard acceleration. I have read stories of peeps putting new springs on and having their cars too high in back.....Does anyone have some wore out leafs they want to sell? No, just kidding.....maybe. What works for soft, low ride?
Yes they can, if they are shot new ones will reposition the spring changing the height. My rear bushings allow the bolts to sit offset in the bore as does my front, once replaced everything will go back where it belongs adding some height to the rear.
Lowering blocks are the solution to your problem. Speedway sells the best ones, and they are not expensive.
Here's a thought, did you tighten the bolts with the car in the air with the rear end hanging? That could put the front bushing in a bind. They say you shiuld have the car supporting its own weight before tightening suspension components. Didn't say it would gain 2 inches but it will gain some.
I think I did tighten it all up in the air hanging......that would make the most sense. 2" might be a stretch, but easily 1 1/2". I am going to see if "un-binding" does the trick. I will take before and after pics just for the peace of mind of future generations.