It's going to bank left a lot better than it banks right. I would have reduced it some but not all. 3/8" does seem a lot, but not knowing the width it's hard to say. 2º or 3º in a Cub style is by no means excessive. A 4" wide firewall with 3/8" tip is 5.379º if I remember my trig. I would have put 4º, or 9/32" +/- before I just eliminated it.