Something like that would work if it does in fact fit and the wire is long enough. Not sure where your current antenna is. You might have to remove some panels and parts to replace it.
here's some reference links, in no particular order:
Rear speaker wiring https://www.youtube.com/watch?v=WNoTV8pd4hQ
- purple wires are all positive every speaker has the same plug, yellow wires are all negative
http://s95014253.onlinehome.us/63104/42204.html
https://www.youtube.com/watch?v=djOkNpkkWaA
https://forums.nicoclub.com/300zx-stereo-installation-write-up-t572341.html
http://www.zhome.com/ZCMnL/PICS/stereo/stereo.html
https://www.youtube.com/watch?v=o8Po7Swuqws
https://www.youtube.com/watch?v=-kUOZVb8XKU
http://www.twinturbo.net/nissan/300zx/forums/main/view/1035247/Bose-Radio-Wiring-Diagram.html
https://www.youtube.com/watch?v=GWorF0A9huI
https://www.youtube.com/watch?v=hOmZgXSXwfY
So basically you reuse the factory speaker wires, remove the factory amplifier/speaker combos and either use an adapter ring or make your own out of 1/8in plastic or wood. As far an antenna, I ditched the factory one and went with a dashtop unit: https://www.amazon.com/gp/product/B07GVFWV15/