Um guys I figured it out. For the rando finding this post a decade later I'll lay it out.
So I opened up the laptop again and took a look at the primary drive with the heat shield. Same length 2280 and the screw fit just right. When I put the primary back I realized I had to lift it a bit for the shield bit to slot in. Then I went and checked the new drive. Turns there was some space right below the actual slot that was high enough for the SSD to slide in and also tight enough to feel like a slot and hold the SSD somewhat in place.
So yes, stranger years from now, we essentially:https://youtu.be/-zHVW7Zy_vg?si=IgvG8HPxE4cqW2wO
Thanks guys for the help.