Use a recommended old school painter if you can. They'll tint it themselves to get as good a match as possible and do spray outs first to check it.
I remember everyone raving about the 'Prologic' computer at Morellis years ago that would examine the sample and match it spot on no substitute for a good eye and matching skills IMO
Not keen on the base and clear option if the rest of the car isn't done in that way myself and it's a proper motor