@XxXpumpXxX If you do not have infinite box enabled I think you can simply install the clean game and remove the modded one although you prefer to not to. If you have enabled infinite box and have more items than the limit when you open on the clean version you are detected as a cheater and have very high chances to get banned. So the following method is what I've thought.
I haven't tried myself but maybe doing what
this thread says can help you. Some time ago I followed this Alternative Method #3 under "
How to login to Google+ on modded games"
Method #3:
1. Delete "META-INF" from modded APK.
2. Copy "META-INF" from normal APK(From apkpure or similar site) to modded APK.
3. Sign the modded APK with zipsigner.
4. Install normal APK(From apkpure or similar site) and login with Google Play.
5. Install the signed mod APK over and launch the game.
Note: Please be sure to use the game version is the game!
to be able to login to Google+ in a game. It worked perfectly but unfortunately I haven't be able to check if payments were enabled because there are no in-app purchases. My guess is that if you are able to login to G+ then you should also get the shop to work. You should not need root to run zipsigner, the author of that thread doesn't specify it so I assume it is not required.
Note: when there are new updates you have to repeat steps 1, 2, 3 and then overwrite the APK you get after step 3 over your game.
I can't try myself because I should put more than 1600 characters back to favourites and redownload all of their artworks (thanks to the last game update that requires to open character information to favourite it), this is also TM period so the time to do it is not very much. I'll see if I can try this method creating an account on another device when I have the time.
EDIT: if someone already tried a method similar to this or knows if it works please let us know so we avoid installing all of this game.