There used to be a flattening agent that you add to laquer when I was using laquer to paint cars, but it was sold by the quart, might be a bit of overkill. If you spray  your paint very dry it might work. is this going to be under a canopy or will it be exposed to fuel?
my cockpit detailing I use Acrylic paints from the craft store, the have a "flat" clear that you brush over it when your done painting and it works very well. they also have a gloss, and a satin clear . small bottles, about 4$ each as I recall. Dries fast, covers well, and is easy to clean up. great for cockpits

Allan Sig makes a flatting agent for dope. Virginiahobby sports list it on there web site

There used to be a flattening agent that you add to laquer when I was using laquer to paint cars, but it was sold by the quart, might be a bit of overkill. If you spray  your paint very dry it might work. is this going to be under a canopy or will it be exposed to fuel?

Its an open cockpit design (Chevelle),  but will have a RE muffler with exit on bottom at leading edge of wing.  I dont think the cockpit (at the trailing edge of wing) will be exposed to any fuel..