Well I managed to find some shop time and made a small-ish milestone in my book. Hopefully I can keep the momentum going!
I hooked up the battery cable kit that I purchased. I wanted to run the positive cable like it was from the factory - through the grommet on the passenger firewall gusset/brace.
I needed a longer cable to match the OEM for this and
@Fourrunner was kind enough to make one up for me.
I had my reservations about routing the cable this way. There is no main fuse on the positive cable. Since it's kind of loose, the cable could vibrate, rub through the grommet, and then eventually the cable leading to a not so good sparky situation.
I took a good look at the 57 year old OEM cable and there isn't a rub mark to be seen. Same with the grommet.
Part # 90480-01050 for the grommet. NLA unfortunately. I am slowly going through all of the firewall grommets. This is only the second one so far that is NLA from Mr T.
With the correct length cable and routed this way, it sort of "floats" here if that makes sense. A natural fit if you will. I'm not too worried about it rubbing through but at some point I may add an inline fuse.
All buttoned up. Negative cable was a perfect fit. The kit came with an engine to frame ground cable but I'll leave the OEM one for now.