I’m a big fan of the original Kit Kamper and appreciate your desire to stay original with the windows. I’ve got a permanent search for them on eBay and in 10-years have never seen anything like them being listed. Attached are two images of the original Kit windows (images taken from the internet— not mine) for your reference. They were mitered corner awning style with a big push-out bar on the inside that latched below the window. A more common window that was similar in style was the Hehr Standard 1418-A, also long out of production but still available on eBay from time to time. The Hehr version was made to fit a 13-7/8” x 18” rough opening. For comparison I’ve also attached two images of the Hehr windows on my 1947 Kit reproduction.
Cheers,
-Rob



