Although I am not totally familiar with that era 4/4 , many +4 owners of that period have improved front end bottoming out by fitting harder springs. (140 lbs from memory) These together with a front end rebuild incorporating hard chrome king pins and spirally grooved bushes certainly did the job. Someone like Cain at Wolf Performance is well versed in this and can offer advice and help (or do the job at reasonable cost)
The SSL front kit does improve the handling by taking the rebound spring out of the equation BUT it generally results in slightly "softer" (but very well damped and controlled) handling so perhaps not the route for you?
However in most cases the SSL front is a very worthwhile mod, it makes the car much better on bumpy surfaces , and the handling is "tighter" so I do heartily recommend it.