You'll be ready for a war bird once you no longer rely upon the dihedral to level out the plane. I fly mine with, or without dihedral the same way and I barely notice it's even there, well, except for when the wind kicks in. I don't reccomend the p51 to be your first, it's wing design is inherently unstable so it's going to do crazy stuff with little direct input on your end, that's what makes it a good fighter. I found the p40 to be more stable, almost trainer like in my opinion, mainly due to the wing design and it has a bit larger control surfaces in the aft section which gives you greater control, especially with recovering it from radical banking.