The one I have here is exactly like the one you show except it is 25mm/1" all the way through, came off a Cox XL Scout ride on, and has the same method of attaching. So if your replacement engine has a 25mm shaft, even with a stepped section it should go on okay. If you did need to make a short sleeve to fit the stepped section that would be a pretty simple job for machine shop to do. I'll take some photos later.
