The cache is not located at the posted coordinates. You will have to guess the numbers to fill the coordinates where you will find the physical cache.
GZ is a quite exposed area, but I trust on you stealth to be able to sign the log without arising suspicion. 
Good Luck :)

S AB° CD.EFG / E HJK° LM.N(P+1)Q

A

Sydney Harbour - EstuaryGC76CFE → Furry Opera Singers GC74YRV → Sydney Heritage Fleet GC75RND → Woolloomooloo GC711E6 → Stairs of Woolloomoolo GC72GJP → The NEON SIGN GC75QVG → Gay and Lesbian Holocaust Memorial GC75DYC → Taylor Square GC75P56 → Dr Chau Chak Wing Building GC755XN

B

Sydney Harbour - EstuaryGC76CFE → Furry Opera Singers GC74YRV → Sydney Heritage Fleet GC75RND → Woolloomooloo GC711E6 → Stairs of Woolloomoolo GC72GJP → The NEON SIGN GC75QVG → Gay and Lesbian Holocaust Memorial GC75DYC → Taylor Square GC75P56 → Dr Chau Chak Wing Building GC755XN

C

SYDNEY OPERA HOUSE GC74MMK → Sydney Harbour - EstuaryGC76CFE → Sydney Heritage Fleet GC75RND → Woolloomooloo GC711E6 → Stairs of Woolloomoolo GC72GJP → The NEON SIGN GC75QVG → Gay and Lesbian Holocaust Memorial GC75DYC → Taylor Square GC75P56 → Dr Chau Chak Wing Building GC755XN

D

Sydney Heritage Fleet GC75RND  →  Sydney Harbour - EstuaryGC76CFE → Sydney Opera House Rocks - Feldspar GC74PCE →  Dr Chau Chak Wing Building GC755XN → The NEON SIGN GC75QVG → Gay and Lesbian Holocaust Memorial GC75DYC → Taylor Square GC75P56

E

Stairs of Woolloomoolo GC72GJP → Sydney Heritage Fleet GC75RND → A night in a Secret Garden GC70C45 → Taylor Square GC75P56

F

Stairs of Woolloomoolo GC72GJP → Sydney Heritage Fleet GC75RND → A night in a Secret Garden GC70C45 → Taylor Square GC75P56

G

Jerremon Bay GC70KF5 → Sydney Heritage Fleet GC75RND → Sydney Harbour - EstuaryGC76CFE → Furry Opera Singers GC74YRV → Jerremon Bay GC70KF5 → Stairs of Woolloomoolo GC72GJP → Gay and Lesbian Holocaust Memorial GC75DYC →  Taylor Square GC75P56 → Dr Chau Chak Wing Building GC755XN

H

Sydney Heritage Fleet GC75RND → SYDNEY OPERA HOUSE GC74MMK → Taylor Square GC75P56

J

SYDNEY OPERA HOUSE GC74MMK → Sydney Harbour - EstuaryGC76CFE → Sydney Heritage Fleet GC75RND → Woolloomooloo GC711E6 → Stairs of Woolloomoolo GC72GJP → The NEON SIGN GC75QVG → Gay and Lesbian Holocaust Memorial GC75DYC → Taylor Square GC75P56 → Dr Chau Chak Wing Building GC755XN

K

Sydney Heritage Fleet GC75RND → SYDNEY OPERA HOUSE GC74MMK → Taylor Square GC75P56

L

Sydney Heritage Fleet GC75RND → SYDNEY OPERA HOUSE GC74MMK → Taylor Square GC75P56

M

Sydney Harbour - EstuaryGC76CFE → Furry Opera Singers GC74YRV → Sydney Heritage Fleet GC75RND → Woolloomooloo GC711E6 → Stairs of Woolloomoolo GC72GJP → The NEON SIGN GC75QVG → Gay and Lesbian Holocaust Memorial GC75DYC → Taylor Square GC75P56 → Dr Chau Chak Wing Building GC755XN

N

Sydney Heritage Fleet GC75RND → Dr Chau Chak Wing Building GC755XN → Taylor Square GC75P56 → Stairs of Woolloomoolo GC72GJP →  Jerremon Bay GC70KF5 → SYDNEY OPERA HOUSE GC74MMK → Sydney Harbour - EstuaryGC76CFE → Sydney Heritage Fleet GC75RND  

P

A night in a Secret Garden GC70C45 → Sydney Heritage Fleet GC75RND → Dr Chau Chak Wing Building GC755XN → Taylor Square GC75P56 → Stairs of Woolloomoolo GC72GJP → Jerremon Bay GC70KF5 → Sydney Heritage Fleet GC75RND

Q

Woolloomooloo GC711E6 → Sydney Heritage Fleet GC75RND → Sydney Harbour - EstuaryGC76CFE → Furry Opera Singers GC74YRV → Woolloomooloo GC711E6 → Gay and Lesbian Holocaust Memorial GC75DYC → Taylor Square GC75P56 → Dr Chau Chak Wing Building GC755XN → Sydney Heritage Fleet GC75RND