It looks like those springs have sagged a little from old age and negotiating too many bumps. Look at the distance between the frame and the rubber bump stops. It's going to bottom out on the stops anytime a serious bounce happens. I'd suggest getting the springs re-arched, adding a leaf, or finding some less-tired springs. Chances are the drag link is already out of level due to spring sag, so a lift MIGHT bring it back closer to right. I'd prefer to restore the suspension to its original condition rather than apply a Band-Aid fix.
Jerry
