Washer pump - check the pipes on the back of the pump haven't fallen off and that there's fluid in the bottle. Then give the plunger a few pushes, it might be that the pipework needs repriming. It does work, and quite well, or it did when I tested it out.
Seatbelts - fronts are from a P6 and the 1100's originals are fitted in the rear, if I remember what Cats told me when picking up the car. Not sure why the passenger belt is missing, I know the latch side is there because I tucked it into the seat and I didn't have cause to remove the other half, I assume it was in the car. Perhaps it wasn't?
Indicators - I can't remember if I replaced the driver's front, or if that was the dicky holder. A new bulb/wiggle of the old bulb should sort it. The stalk is a bit of a duff connection, after a bit of use they do wake up and work reliably but I think the connections are corroded slightly from lack of use.
You may need a battery clamp too, I can't remember if there was one or not. You'll definitely need a rocker cover gasket, in part because it's weeping and because being an A Series, TADTS.