Yes. I had forgotten about Megow. Megow was riding high before WWII. Their "Ranger" free flight kit, designed by Matt Kania, kept them in business.
Comet kept busy during WWII with their 10-cent kit line. Kit contents were surprising; hardly anything in the box. Colorful box art sold most of those kits.
Cleveland Model Supply was sort of active, although I'm not sure about their kits, since I never bought one.
Solid wood model kits were plentiful. Not only airplanes, but tanks, cannon, machine guns, trucks. All models in soft pine.
You could buy engines from O&R, but it required an application in writing, that the engine would be used for educational purposes. O&R put together a few of the .23 engines during their off-hours, using mostly parts on hand.
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Oh yes. Forgot to add. I'm 87 years old. I was an 8 year-old model builder when WWII started. Kept building models all during the war and , of course, after. I was one who got a new O&R .23 for Xmas in 1944 (my parents signed the application for me)