This may be late but may help those who view and wish for the same thing.
If you wish to import the portrait/body images of Strive for Power's characters, you may use the STEX files of the character body and portrait instead of a png file. Simply locate the desired character's STEX file and place it to the appropriate location.
=Directions=
1.) Go to the .import folder of Strive for Power's directory and search for your desired character via manual search or search bar (example: "Emily")
2.) Select the desired variant of body portrait of the character (example: "emily2happy.png" followed by numbers/letters) and select the desired character's portrait (example: "emilyportrait.png" followed by numbers/letters)
3) Move these files to the appropriate custom body and portrait folders for your Strive: Conquest game (typically in your appdata/roaming in a file under the game's name)
4.) After creating the desired character via cheats or save editing, you may now select the imported portraits and body via the customization tab of the character.
Additional Information: The images may not be in the same dimensions as normally used by the game and are off a little.