Peach's Castle would've been the land's main entry point for this incarnation. Enter through green warp pipe outside the land, enter the land through Peach's Castle... and yes the interior would be straight out of games like Mario 64 and Odyssey.
I haven't posted these in awhile, but here's a description of the layout based on official concept art:
View attachment 10097
View attachment 10098
The labels are based on the old KidZone plans, and should line up with the model photos pretty much exactly.