Which F-4?
I assume you mean the Lanier ARF because you are talking 45 sized- if so:
This plane comes out nose heavy so the Webra would get my vote... I love the Rossi but it is heavier-
I run a YS-45 on a 10x7, the Webra or Rossi would pull those fine or 10x6- I tried a 9x9 but it no workie...maybe 9x7 or9x8?
Let me know if you have any questions about the build- I have many flights on mine and it is great!
james