No that is not necessary, the vehicle does not have a 1920's paint job it is a 1987 paint job which is still classed as a modern day paint finish and easy to match irrespective of whether it was sprayed in acrylic, cellulose or twin-pack.
The vehicle paint code for this particular colour Gunmetal silver relates to a twin-pack system and because it is classed as a modern metallic colour it would be very easy to obtain the correct match because there is only ONE paint shade for that colour, no variants to make things more complicated, the paint mixing formulae and paints are still available.
I have never know any competent paint sprayer to have to initiate a full respray just to match the colour unless the colour was unknown. You can still match colours from the thirties onwards as these were mostly sprayed, it is the older coach painted finishes that prove difficult to match, but even there you can in some cases match severely faded paint finishes.
Stephen.