30 hours tops. Including time taken to find new grommets at the wreckers, and putting connectors in places to allow engine to be removed easily.

I would recommend:
1. putting a relay into the 'parking lights' circuit as they are susceptible to rust, and can melt wires and connectors.
2. putting another relay in for the headlights and upgrading them to halogen H4 inserts.
3. modify/splice the alternator wiring into the 1200 wiring.
4. Upgrade the electricals to use separate fusible links for 'datsun stuff', and 'nissan stuff'.
5. consider wiring for boost control solenoid.
6. thermo fans
7. intercooler pump spray
8. car alarm.

It's possible to do all this in a day if you have more than one person working on the car, and it's done at a workshop with all the parts/wire available.

Hope this helps.