Big job and you will lose a lot of sq. footage so keep that in mind.

schnable1:

Stairs are math and math can be cruel. They put the spiral in to save real estate. You're going to have to spend real estate to get the run conventional stairs require. And you're going to have to spend the money to do it too. I don't even propose stair changes any more; I never get the job. No, I'm not "too expensive", I know how much work and risk is involved.