Rich,
My bending experience has been with flatwork, so be forewarned.
Different woods have very different "bending characteristics." Cherry, for instance, can be bent, but is a CIB to do, whereas ring porous species like Oak, Ash and Mahagony bend beautifully. The normal rule is 1 hour at 212* per inch of thickness. The factories cheat on this 'cause they have high pres/temp steam and hydrolic bending machines.
Normally dimensional stock is used for bending. If you are bending turned spindles with different diameters and profiling along the way, I would anticipate you're going to run into some special problems, not the least of which will be bending marks and changes of the profiles. Again normally, you'd make a bending jig to match the final curve, heat your stock, and then clamp it in the bending form to cool. The wood takes the curve of the form and all's well.
Now, I think you've got to make two negative form profiles to match your spindles and their intended final shape, but also curved, so that you can clamp the pieces in the form. THAT's gonna get complicated to say the least.
Good luck, and post a pic of how you wind up.