Pretty car! FAIW, it's got a '77/'78 bumper and molding on the front -- probably wrecked at some point. Then again, with cars these old, it would be unusual to find one that has never been wrecked.
The engine bay photo is pretty fuzzy, but there does seem to be an assortment of hose types, suggesting that replacements were only done when a leak or break was discovered. I'd recommend replacing all of that junk with new. It should cost all of $15.
The wiring repairs are also pretty amateurish. There are probably some good youtube videos on making wire junctions -- small learning curve + a minimum of equipment -- not rocket science. My usual approach is to crimp, fill with solder, and then insulate/seal with marine-grade heat-shrink tubing (which you can buy at Harbor Freight). I'd remove all the nasty looking splice work and replace with new lengths of wire. And depending on the condition of the electrical connectors, I'd replace those with new ones from ebay (search for "280Z injector connectors"). The 2-wire ones are readily available. The 3-wire (throttle position sensor) is available from more modern vehicles in the wrecking yard (e.g. Volvos). The large airflow meter connector is probably fine, and you would have a hard time finding a good replacement anyway. And you should take a look at your fusible links (under clear plastic covers on the passenger inner fender). They might be crusty and unreliable. The covers are often gone, exposing the contents to moisture/corrosion.
You should pull off the battery cables, clean up the posts and connectors, clean the top of the battery, install felts, grease the cable clamps, and reinstall. Heck, you could probably use new cables, judging from the corrosion.
All of this is detail work that you can do with a minimum of tools, knowledge, or strength. You'll probably eliminate a few problems in the process, without even knowing you did it.