I dont think you want the "scapula in the back pockets" for deadlift, even figuratively. s/b Nuetral.
maybe? just sayin
Your lats keep the bar close to you, which stops the bar drifting forward which almost always precedes the lower back rounding. They also create stability between the shoulders and (opposing) hips, which helps again to keep the lower spine in neutral.
"scap in the back pocket" is just a form cue to help you activate your lats. There's lots of different ways to think about it or coach it. It's more of a set up cue, and sometimes just pulling the slack out of the bar does the exact same thing. Also, I tell people when they're setting up to imagine i'm going to tickle them (under the arms), and the natural reaction is to tighten the lats.
For the OP, I would check your neck position, too. If you're looking way up, with your head cranked way back into hyperextension, then you change things in your shoulders. The scap ride up. You shorten the upper traps. You can't get as good a breath of air (less stability). Also, you mentioned the neck specifically. When setting up think about bringing your chest up to your chin, and keep your eyes looking on the floor about 6-8 feet in front of you, rather than way up at the ceiling.
Also, as a general rule, you don't want to mess with necks. If your neck hurts you need to get it checked out. Since you're most likely going to atleast try and train anyway, then it's worth trying to put your neck in a safer position but, atleast consider seeking a specialist to check things over.