Sean - Since you have read most of my trials and some of my pain, I really have few comments:

Solder and shrink wrap are best - and there are two kinds (or more!) of shrink wrap. The shiny stuff isn't as good as the flat finished. The flat I believe is marine and has some adhesive and will shrink tighter.

Grounds are important even with a steel car which I believe yours is as well. You need a ground from an engine/transmission bolt to the chassis and a second, also from the engine to the body. I used some flat braided ground straps that I bought from AAW at an NSRA meet. I also have more grounds for various pieces on the body and behind the dash. These are mostly wire brushed to clean steel areas that had a .25 brass bolt, a couple of SS star washers and some dielectric grease. Any grounds, best to use star washers.

Tie wraps on wires from the module to the rear of the car and if under the carpet will not easily fit in convoluted tubing - and will upset your upholsterer. I originally tie wrapped mine, but ended up removing those under the carpet area and wrapped with orange 3M Scotch #35 electrical tape. Not necessarily the best way if a repair, a change or more wiring is needed but my upholsterer is happier, tho not much.

Dash - by your photos it appears that you haven't done your dash yet - and with the pre terminated EZ wire assembly, you might want to not get too far before you put it together. If you still can, and it's not welded in place, consider pulling the cowl top cover off or get a standing appointment with a chiropractor

Anything else - well, I can share pain in wiring these cars