Steve, if it's only the cost of a spray can you can afford. You probably shouldn't have bought a 25yo Skyline
But as per your question here are some suggestions
Paint the rear view mirror and cabin centre light in black - looks good
Also remove the faded or peeling material from the doors and rear cabin and paint them in black.
Remove the rear wiper and put a flat rubber plug in it.
You could remove the glass lenses from your headlights (oven method) and paint the non reflecting parts black.
Change the triple gauge and cluster lights to LED's
Personally I'd give it a full service for starters and work on things like brakes, steering & suspension