Need some help!

So now I am wondering if the spindles for the Kelsey-Hayes are the same as for the drum brakes... Is there a difference between the Kelsey-hayes, 9" and 10" drum brake spindles? Or is it all the same spindle? Any other parts I have to think of to replace?

All of the 3 spindles that you mentioned, are different from one another.
They are unique to each drum brake size, and then for disc brakes.
Kelsey Hayes disc brake spindles, ARE NOT the same for either of the drum brake diameters.
A totally different design.