Swapping the guts of one phone into the body of another?

I have two iPhone 6 phones. One has a bent body, fully functioning but the screen is damaged from having been bent. We have the other 6, which is in perfect physical condition but the Apple ID cannot be unlocked (it belonged to a family member who is unable to unlock it and has since upgraded, gave it to us for parts). I want to dissect both phones, and put the “guts” of the bent phone into the body of the other, but what I’m wondering is how much of the guts do I need to transfer? I’ve seen the guide for replacing the rear body of the iPhone 6, but it removes and replaces everything, including camera hardware, vibrator, etc. Those all work in the unlockable phone, so I’m wondering how much of the guts I can leave intact, and how much I need to transfer.