Mobilize, the S.E.5a already exists.
As far as the other planes go, I think the Bristol F.2b is definitely worth considering, but so is the Hawker Fury which can be considered an "advanced biplane" - the last first-line biplane fighters before the introduction of high-performance monoplanes in the late 1930's.
Wyrm, I must commend you for all of your new units!
You seem to be almost one step ahead of me in making "forgotten" airplanes, like the Piaggio P.108 or the Amiot 354 and the Breguet Bre.691, not to mention your outstanding recent MiG's. Thank you so much! I am a big fan of your Art-Work...