I believe I got my original Lionel set for Christmas 1941 or 1942. I could be wrong as I cannot remember playing with it in the home we were in during WWII. (I did have the 1943 paper set.) We moved just as the war ended in 1945 when I was nine. In any case, I do remember how the 1700 series caboose looked without any ladders between the frame and the roof, so I know I'm correct about the cars. The set probably had the uncoupler track included as the gondola, I believe, had one link coupler and one box coupler. And of course it had the 2-4-2 engine with the E unit near the cab.
I would imagine that my Dad bought the bigger cars as thinking that it gave us more bang for the buck. (The kid across the street had a 1688 with the smaller O-27 cars.) I can't remember bringing the set home from downtown Indianapolis but I do remember the crowd watching the layout in the store. Would the Ives cars still have been available in an un-cataloged set after the war? I've been able to purchase a set of the cars and the Columbia loco as well as the uncoupler track. I got a junk caboose to get the box coupler but will probably use the box car to put it on instead of the gondola since I'll most likely use a screw/washer/nut to re-attach the truck instead of a rivet. At my age, (80) I'm not going to get that involved in tinplate again. I just wanted a set of cars to let the cats chase on the living room floor.