The list I've done.
Extra sound proofing in the way of flashing tape and carpet underlay.
Black hook type wiper arms and proper blades, bought for peanuts years ago when everyone went made for the rubbish chrome tat.
Halogen headlamps, brighter bulbs and extra relays as to not fry the original unfused wiring.
Electronic ignition, pretty much been a fit and forget with no more points to mess with.
Electronic flasher relays for the indicators and hazards, so they flash like a modern car and not lazy like the originals.
A larger 45amp (standard is 35amp) battery witch makes starting a lot easier.
Headunit and a pair of 6x9's under the rear seats, as with the extra sound proofing you can actually hear it.
And a cigarette lighter socket for the sat nav and phone charger.