Take a look at The Retor Ryder Headset
by Genuine Bicycle Products. It allows you to use a 1 1/8” non-tapered fork in an older bike that uses a 1” threaded headset like the older Schwinn’s. You will have to check your head tube as it will only work if the inside diameter is 30mm. I ordered one and install a Suntour XCR suspension fork onto an old Schwinn Typhoon last week that I’m building.