I too, think a warbird should be plane #3 or 4 (especially if its' a taildragger-)- a entry level low-wing would be perfect (I always recommend the 4* also

) But if scale is what you are after, the T-34 mentioned above flies great, lands relatively slow, and looks the part- A PT-19 is also a great low wing trainer style warbird- The GP AT-6 looks pretty good but never flew well for me, the Kyosho is much better quality wise if you have to have a Texan.
Sounds like you have the trainer down pretty well, Just pay close attention to the CG and control throws on the aforementioned planes as it makes a much bigger difference than with a trainer -
Keep us posted! From the 2nd plane on it just gets to be more and more fun!
james