That Zip kit is fairly good, thorough but also includes at least one pressure valve that shouldn't be used if a better(later design) kit is chosen. Sonnax developed that Zip kit many years ago, before another individual kit item they came out with a few years ago. You can look at and read about all of the various items they have for the 4R70W, on their site. I would prefer to buy the needed items separately, which ends up a little cheaper, given the internal parts you don't use(made for a rebuild(all of it is apart)), and that one pressure valve not needed.
For what you seem to be after at the moment, get it working right again, not necessarily perfect with all upgrades(A Jerry's Mod would be part of that), plus accumulators, I'd do just the solenoids and see what it achieves. The o-ring kit I mentioned is easy for anyone to put in with the VB out, while the various other VB kits can be more tedious or difficult. I'd want to do those at a slow pace and not in any rush.
The shift solenoids do have two paired into one unit, I forgot that. Those on the side of the VB are kind of low cost, and also easy with the VB out. The VB is a contained unit, no check balls will be lost, but there is a pair of small springs up inside the case near the front. If you drop the VB, do it slowly and watch where those two are. They are slightly different and you would only notice with them out and side by side, separating the parts to compare. The tiny end piece is different among those two, all together at a glance they look alike. Other than those little springs assemblies(they are fairly sturdy and lowering the VB smoothly will have them end up standing straight up or barely stuck up inside the case), the VB is a single assembly that is easily handled.
Note, don't mix any early model 4R parts with a later model, the solenoids and the internal wiring don't mix. That means before or after the 1997/98 model years, so you need a 1998 or newer solenoids etc. I think that plastic assembly with wires is called the metal frame or similar, the early ones needed to be replaced, the 98+ are fine to reuse.