I would not recommend 660 engine for cultus. Rather you should go for 1nzfe engine, the one in vitz with auto transmission.
This will need some modifications in the engine bay but would be best in performance.
If you want your car to perform like wow, then go for g13/15/16 swap. that may not come with auto transmission but your car will become a beast.
If you are in pindi/Islamabad you may contact @dani_kk for further guidance.
In Lahore you can go for caregar restomods in johar town