Your project sounds like a lot of fun. Dig in a lot of compost and build an Alpine shade garden.
My favorites would be Soloman's Seal (especially the variegated one), Bleeding Hearts, dwarf Hostas (like Blue Mouse Ears), Coral Bells. Dwarf everygreens like Dwarf Hinoki Cypress. And cold hardy azalea. My fillers would be bulbs like blue bells and crocus. I also love Astilbe.
