I am worried that even though the length is close, just one cm difference, there will be other differences in the shape, height or pole positions that will make the fit difficult or impossible.
I have a 4/5 that came with an ill-fitting third party awning and the porch awning I bought will also need a lot of changes to fit and is not very sturdy and is quite small.
I could arrange a test fit, but it is a long way to go if there is no hope.