Revisiting this after a couple of years and an Airbus rating, I'll add the following that might not be strictly "required" but quite useful:
- RNP data block on PFD or ND
- a larger PFD attitude sphere and/or "full screen" horizon with overlaid speed and altitude scales; the pitch gradation is very small
- a vertical situation display
- more than one category of APT/CSTR/etc. at the same time
- a speed deviation indication (like on HUDs)
- automatic power-on of IRS
- a flyable FD guidance when using the FPV
For a 40-year old design it's quite impressive, still.