Brush finishes.... here's what I know regarding history...
Auburn and even Cord did brushed finishes. However, the paint was applied with a VERY fine haired brush, the likes of a sable haired brush would have been used. Then in between EACH coat, there was a watery mixture they would hand buff the coat with with was pretty much a fine pumice in a liquid they would mix up and apply, rub and apply yet again. Of course as you can imagine this took a while, but there were more than one person doing it!
Other than that,.... yes, as I've mentioned to you in the past when we talked paint, right from the fellows that were there (in the 1930s and 40s) you used what you had on hand. rarely did anyone have an air compressor and a paint gun! if you were lucky enough to have a friend with that combination of tools, then, yes, you'd try your hand at spraying the finish. Buffing between each layer,..(hand rubbing). Though most fellows could only afford primer, or primer and a color coat. They did what they could as best they could with the materials at hand. This info comes from two fellows in California that were hot rodders in the mid to late 1930s. One is 92 and the other is 89 years old.
"The beauty of life is more the crying baby than the great orchestra." -Woody Guthrie