Make sure you do a really good scrubbing cleaning of the textured paint before trying to match it. You might find that the machine is quite noticeably lighter in color when it is cleaned really well. I swear I must have taken off a pound or two of dirt and tobacco tar from the machines I've cleaned in the past few years.
Pete, thanks for the tip on the latex caulk undercoating! Interestingly, the Raleigh bicycle company used to spray a coating of vulcanized rubber on their steel frames, then would prime and paint with several layers. Our his and hers set of Rudge bicycles from 1956 and 1958 have incredible black paint because of this process of rubber undercoating; it seems to create a resiliency to the paint to prevent chipping and spread of rust.
Phil Forrest
