An early planeset with those Karnak mentioned (I-153, I-16, CR42 and Gladiator) is probably a loooong way ahead, judging from the current pace.
You'd practically need all of them, and some more to make it proper anyway. Swordfish, PZL-11, Early Stuka, 109D.....Henchel...
I-16 is my vote, for it saw a lot of use from early on, and can be spread across many models.
And then, don't forget many others ready in '39 and used in '40, - D520, the Fokkers, the Brewster, etc etc.
Have faith though, HT has made a bipe simulator before
