Is there a certain finish you are trying to match? If using an airbrush I highly recommend Testor's Model Master lacquer. I found most of my models match a mixture of 75% semi-gloss and 25% flat, while others are more of a 50/50 mix, which is what I actually prefer. Even though I use a ventilation system to eliminate dust, I still like knowing that I'm using something that dries before anything has a chance to adhere to the finish. It is the easiest way I have found to give you an absolute flawless finish. I have actually repaired damaged paint from excessive smoke fluid on multiple brass steam engines by simply reshooting the clear coat to blend everything together again.
I have also had success with a complete flat using Tester's Dullcoat as well. It all depends on what your preference is.
Good luck!