Cutnshoots
Hello & Welcome to the Forum.
Table top to ceiling layout's are common, especially in large scale indoor layouts.. They are/were seen in restraunts.
Normally you want to use a 2% grade for your average locomotive & consist.
With traction tires and a short consist 4 to 6% grade is feasable.
With a geared locomotive (Climax, Heisler, etc) you might be able to climb an 8% grade with a light consist.
Happy Rails!
dave