Sorry to say it's not easy to even suggest a price since they have become so incredibly rare & with parts supplies almost non-existent condition & healthy running becomes a HUGE factor, as does finding the right buyer since most people have never seen one for the last 20 yrs & have forgotten their existence so few are looking.
Having been cheap to start with few were well cared for and their lightweight construction and high-revving engine made them highly susceptible to rust & damage .
At least they are distinctive & tiny enough to be memorable when seen these days.
I know one insurance company proposed $1700 for a good, registered '73 Z360 hardtop but rarity & condition makes values HUGELY variable.

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www.cardomain.com/id/79cord
'79 Accord, '89 CR-X SiR, '81 Prelude, '74 Z360 H/T, '71 Z360, '64 S600, '75 Lancia Beta.

I used to have a massive collection, including a Z600, didn't pay more than $1,000 for any of them but it was a while ago. I promised if I ever bought another, it'd have to be a good runner, as parts were impossible to find. I shouldn't register interest, as the missus would kill me, but where abouts are you? I'm in Adelaide too. PM me if you like.

Cheers,
Duane