Sounds like an awesome project. If I were building a high horsepower 280zx I would get the following.
1. CP Pistons, Carrilo Rods
2. High strength forged Valves, Valve Springs
3. Custom Intake manifold This one is just 😲! https://protunerz.com/collections/intake-manifolds/products/l-series-datsun-nissan-intake-manifold-fuel-rail-throttle-body
4. Custom exhaust headers
5.Injector dynamic injectors
6. Delete distributor, install crank angle sensor https://protunerz.com/collections/plug-and-play-harness/products/datsun-l-series-crank-pulley-with-trigger-wheel-mount-and-cas-sensor
7. Install coil on plugs with igniters https://www.diyautotune.com/product/ign-1a-race-coil/
8. Buy a MS3Pro Ultimate ( If you've never used a tuner program, Tuner Studio is a great program to learn on)
9. Run custom AR lines, a nice FPR, High flow Fuel Pump, Custom Fuel Rail.
10. Tremec TKO 600 (Modified Bell Housing, Custom Made Throw Out Bearing, 1987 300zx rear differential R200
11. Garret t3/t4 or a t/4 t/4 (more info on this can be found at this amazing 280zx high horsepower build. Go and check this guys page out http://www.angelfire.com/extreme/280zxt/, he
has done incredible modifications
12. 3" Piping all the way back
With your bored out engine this would get you nice high horsepower build