Clark and Friends,
John Henderson's CLASSIC FREIGHT CARS, v.1, has two photos of GA boxcars on page 39. GA 29399 from series 29300-29449 is a total rebuild of a 1924 car with steel sides, outside vertical ribs and no diagonals. It appears to be dark gray with black ends, black doors, and possibly a black roof. The roof is definitely peaked. This is not the prototype for the Tichy car, but interesting. This photo is dated to 1959.
On the same page is GA 19682 from series 19500-19799, and appears to be a steel-sided rebuilt of a USRA car, retaining the original bracing pattern. This car is BCR and definitely has a peaked roof. This photo is dated to 1956.
In Henry Maywald's CLASSIC FREIGHT CARS, v.7, on page 27 there is another GA car, 19755 from series 19500-19799. This car is sort of silver/aluminum colored, but so grimy it is hard to read the black lettering, and I can't see what color the ends and roofs are. This car has roof hatches (probably four) which are very flat and also hard to see, and is marked "RETURN EMPTY / GA.R.R. ATHENS / FERTILIZER LOADING in white to the left of the door. I cannot see for certain whether the roof is peaked or radial, but it looks slightly curved. This photo is dated 1966, and could be a rebuild from beyond our period of interest, but shows that cars in this block could be very different.
I hope this is of use to you, and doesn't muddy the waters even more.