Sakura Taisen has been favoured best in its rawest form; the game.
Side products such as toys, models and logo-ware have not been massively overproduced.
This subject is more likely to be achieved by self design effort than grueling websearch.
Sakura Taisen 2 uses the same units with minor character additions. Hajime Katoki (Kai) had gotten involved and a second design for the Koubu was modeled; noted quickly by the distinctive triangular vent on head and flared crotch shield.
Sakura Taisen 3 has the Koubu-F, which I do not know if Sakura gets one in the subsequent Sakura Taisen 4.
This starts you at two (possibly three) "Sakura's Koubu" to work.
The bulk of featured materials is more illustrative than documentive, and I have not seen any orthographic set of views.
tikitiki_m's image could be a fanart custom model as far as I can determine. "Non-canon", at least it hasn't appeared amongst what I've documented yet; I don't have anything from the recent release of Sakura Taisen 5.