We are looking at resource/ui/HealthIconPanel.res if the file is missing in our hud we can take it from the DEFAULT HUD FILES as always
After we added the file to our hud we can join an offline server and spawn a bot to edit the floating number. We need to work with both "wide" and tall" of "HealthIcon" until the number is completely visible and centered with the body.
Note that the floating heath is only visible if tf_hud_target_id_disable_floating_health is set to 0.