They all have different angles from stub to strut, strut tube length varies and spring cups are different. Find the length of your bilsteins and use the strut that will fit best, you can get spacers machined to fit underneith the insert if you have to take up a few mm.

If you have adjustability in your tops and lower arm, you would want to get a strut with a lot of wheel clearance, 280zx and R30/R31 and Bluebird are all like this.

All wheel bearings are identical for anything from sunny all the way to Z31 300ZX.

See here for lengths of different struts.