Solved, sort of. I'm cursed. My front wheel is 36 hole, and since both hubs are black LX's I thought the rear wheel was also a 36 hole. Imagine the shivers down my spine when the bike was dismantled and I didn't understand why there was a 4 spoke offset. I re-laced twice, and decided to count the holes on the hub. Of course it was a 32 and I spent a whole afternoon hunting for a 36.
The shop is willing to take it back for a 32 hole X317. Not too convinced by the lower model at the same price. Even more so when tomorrow is just the day before the bike jumble where I'll find a lot of stuff, very probably.
But if I find the rim tomorrow and lace it up, I'll be good to go on Saturday. 3 days wasted is already too much. I feel so stupid.
But as the bike awareness campaign said "it's easy to miss something you're not looking for"...