Thanks for your help Moonman - somewhere I goofed in explaining the measurements - it looks like I gave you reverse directions.
The stairs are exactly 11' (132") from the west wall and are 21' (252") from the East - so they overhang 6" past the west edge of the North alcove. They sit 4' 9" back from the north wall - 6' 9" from the back wall in the North alcove. That re-positioning should push the track back so that it can turn in the alcove with a bigger radius turn.
Stairs are open underneath - so track can be curved under them - which was my plan. I'll check the rise and run of the stairs again tonight but I believe it's not code (7"-11"). I'm 5"10" and at 11 feet from the North wall (13 feet from the rear of the alcove) my head easily clears by several inches. That's roughly 10 x 10.5 rise - I knew those stairs felt steep! At that rise, a train at a 36" counter height ( I assume most layouts are at counter height?) - to achieve a respectable 10" of clearance- the center line would be set at 117" (9', 9") back from the wall - 141" from the rear of the alcove. That'd cut the stair obstacle to get around to about 41-42"
Check my math - but that should work to aid in rounding the stairs.
