DI's use ATF for power steering fluid.ATF is backwards compatible, so if it calls for Dexron you can use Dexron II or III, if it calls for Dexron II you can use III, and so on.
As long as it is Dexron and is at least the minimun that is required you can use it.

 

So I take it that I shouldn't use it in my DII...

I am willing to try anything to try and get the noise to go away in mine!

 

Correct, do not use Dexron in the power steering system of a DII. If you are 100 miles from home and that is all that you can get, yes, use it.
But DII's use power steering fluid in the power steering.

What noise are you talking about?

 

Jonathan - Did you pull the lifters and inspect them when you had the heads off? It seems that with all the work you have done you have nearly eliminated all the internal possibilities so you may have to look externally. Check to make sure the bearings in the alternator are still good. Spike explained how to check it at the beginning of this thread.