It might be an idea to tell us where you are, at least the general area, some one of the forum members might be nearby.
From a point of view of insight, for me the important thing is to recognize your limitations, none of us is an expert on every thing (although I do know a few people who would swear they are), we each have our area of expertise, and should not be afraid to ask for guidance in other areas. At the very least we're going to get a couple of suggestions that might not have crossed our minds.
The transmission issue sounds like a worn synchro on second gear, so yes, a tear down might be eminent, the alternative is to learn to "double de-clutch" and rev-match.
Regarding shimming to correct for caster - the problem there is that as you go one way to correct caster, you're going the wrong way on pinion angle, and potential vibration issues, to get both correct requires cutting & re-welding the axles, which I would consider a specialist task - if there is a camber issue, I would suspect the axle is probably bent.
Z-links do nothing to correct bump steer, all they do is reduce the opportunity of the drag link fouling the spring - a drop pitman arm is half the solution, the other half is some form of "hi-steer" kit, which raises the other end of the drag link - the ideal is for the drag link to be parallel to the surface the vehicle is sitting on.
Hi-steer kits fall into two types - full & half high - the half just adds a new arm for the drag link on one side, the full adds two arms and moves the tie-rod as well - depending on what kits you can find, the half might be better, assuming that is, that you have no problem with the tie-rod fouling the springs - if you're going with a full high kit make sure the new arms keep the ackerman geometry correct.
With coil sprung vehicles the lateral location of the axle is usually via a panhard rod or track bar, and a workable compromise is to have the track bar and the drag link, parallel & equal length - this doesn't eliminate the sideways movement, but because it forces the body & the steering to move sideways by the same amount as the suspension cycles it eliminate the effect of sideways movement on the steering, which is what the bump steer really is - you can add a panhard rod to a leaf sprung vehicle if you so choose.
Any play, any where in the steering or front suspension contributes to the sloppy feeling - worn leaf spring bushes, those long shackles will add to it, loose kingpin bearings, plus of course the actual steering ends and/or steering box - eliminating it becomes a process of checking them all one by one.
