*Boot image*
- Replace *kernel* and *fstab.mtxxxx*
*system/lib*
- Replace the whole *egl* folder
*system/lib/hw*
- audio.primary.default.so
- bluetooth.default.so
- gralloc.default.so
*system/vendor*
- Replace the whole *firmware* folder
*system/vendor/etc*
- Replace whole *mddb* folder
- custom.conf
*system/vendor/lib*
- Replace the whole *egl* folder
- libcameracustom.so
- libshowlogo.so
*system/lib/hw*
- audio.primary.mt****.so
- gralloc.mt****.so
- hwcomposer.mt****.so
*Build.prop*
Change the following like stock
- ro.product.model
- ro.product.brand
- ro.product.name
- ro.product.device
- ro.product.manufacturer
- ro.build.product
- qemu.hw.mainkeys
- ro.sf.lcd_density
*Updaterscript*
Change mount points appropriately. You can check mount points using *diskinfo* app
Lastly, zip and flash using your favourite custom recovery
This guide should give you an almost bugless rom for the mt6580 Nougat
Try and let me know of any issues that you face
