Unless you have a full history,you will never know if it has been repainted in the past,and if you know for sure it has,ie if original was def tobacco,then there are sooooooo many shades of white,god knows what it would be called.
Paint makers all mix to various codes,so shades may differ.
Davos was a bit grey for me,Artic not crisp enough and later Pendelican is creamy.
Before I went for the full repaint,I looked at 100's of colour swatches,to try and match,but due to the years,sun and polishing the paint had faded it,so in the end I went for what I believe it had been painted with in the mid 90's and that was std Ford diamond white.
AND!! It is EXCELLENT!!!
Black for the sills is easy,either go satin or gloss,mine were huntsman brown whch is hard to find a common modern code for,so I got the best match I could.
Touching up will always be difficult to match on an old car,due to fade and wear,you could always take a sample panel to a place with one of those spectrum analyser gadgets!!