Be sure to get the one published by the National Clubs (MARC/MAFCA). There are cheaper ones out there sold by many of the suppliers but you get what you pay for. There are not going to be many choices so just looking at one quickly might be all you need. Are you a member of a local club where someone might have one you could look at?
Hello, Common color on trucks of the Model A area was Rock Moss green with black fenders.Old episodes of the Waltons will give you a idea of the color.
Auto color library is also a source of color chips and paint for Model A and other vintage cars,do n internet search and should be able to find it, but beware the color chip may look different on computer and it will be a 90 year old sample.