I can’t see the point in replacing the flange, it really is just a spacer.
I’d change the gear return spring (27) and the spring on the selector pawl (20) while I was in there, under a tenner for the pair, but a PITA to get to unless you’re already in there, and the return springs are prone to breaking at ~30k miles in my experience.
mark the position of the pawl (24) on the selector drum with paint pen/tippex before taking it out to ensure you still have proper selection when it goes back together.