The nice thing about the Z18ET is its a factory setup, legal in most Australia states for a 1200. The downside is how available is it, including the wiring harness?
Z-series was a common engine in the larger Datsuns, as it replaced the L-series engine starting in 1979.
Z16S Z18E/Z18S/Z18T Z20D/Z20S/Z20E Z22S
VEHICLE APPLICATION 720 Z16S/Z18S 910 Z16S/Z18S/Z18E/Z18T/Z18P/Z20S/Z20E C120 Z20S C31 Z18P/Z18S/Z20S D21 Z16S/Z18S/Z20S E23 Z18S/Z20S E24 Z20S F22 Z16S/Z20S F30 Z18S H40 Z20D/Z20S R30 Z18S/Z20E S110 Z18E/Z18S/Z18T/Z20E TC22 Z20S W40 Z22S WE24 Z20S
8-plug (twin-plug head) E24 Z20 WE24 Z20S 910 Z16S/Z18S/Z18P/Z18E/Z18ET/Z20S/Z20E C120 Z20 C31 Z18S/Z18P/Z20S E23 Z20 F30 Z18S R30 Z18S/Z20E S110 Z18S/Z18E/Z18ET/Z20E
4-plug (single-plug head) 720 Z16/Z18 D21 Z16S/Z18S/Z20S TC22 Z20S W40 Z22S 910 Z16S E23 Z18/Z20 E24 Z20 F22 Z16/Z20 H40 Z20D/Z20S R30 Z18S
Z-series is the 2nd generation of the L-series engine. So oil pans and mounting is the same as fitting an L-series engine.
Also see L-series Engine Swap crossmember, sump sections.
Z-series uses the same transmissions as the KA-series engines. The bolt pattern is the same as the L-series but the lean is different.
See Transmission section of KA Engine Swap