For colors, I recommend using rhe 3wheeler configurator
You can see the color-combo's of paint+leather
On something vintage like your +4
I realy like limegreen with lots of mettalic flakes, combined with dark green leather,
Or mustard yellow with the same green leather
For repairs its always wise to use a 'big manufacter color'
Like the Jaguar gynmetalgrey on my max
Or the Bentley Sandstone (yellow) that could make a Supersports look more fabelous than the sadly gone Lady Di