That's interesting, I didn't realize they had plans to do any of that. WDW's unload is where the gunpowder room is at DL, dunno if the square footage is comparable though. I wonder if they were trying to "complete" some of the cut scenes.
I can't find many photos of the backstage lift area. Only two via google search. It's obviously unthemed and filled with ducts and such. But you can spot the boats traveling up it before getting off the ride. Just eyeballing it, it looks somewhat steeper than the lift at DL and the boats also like like they travel up it at a faster rate. I don't know if the current lift could sustain the weight of boats filled with people. Unless they were intending to gut and rebuild it.
I assume the area where the boats re-enter the load would be problematic and require demolition and re-building. I don't know what is actually in this backstage area around the bend. Though it seems only a wall separates this bend from the outside queue spillover and part of the giftshop. The archway tunnels where the boats re-enter the loading platforms are extremely low clearance. Only just barely high enough to allow empty boats through. Nowhere near tall enough for boats with people. The queue also travels overhead these tunnels, so i'd be unsurprised if that entire area needed to be torn apart and rebuilt. No idea what sort of concrete, metal and other building materials would need to be dealt with to do this.