The A-arm mod goes back a long time - Jack Arnew was the guy back then at that stuff, and my ex-Hamburger had them.
A-arms are triangles, of course, so picture one as an upside down A, or more accurately a V.
Adding length to the front leg (Arnew) or subtracting length from the back leg, moves the point where they join backwards.
That tilts the spindle rearward at the top, increasing camber. Mine ran about 7 degrees, though 5 is adequate.