hOughy,
Any grade of stainless screw should be fine with Al. You won't have a significant corrosion problem there. Both Al and SS work by forming an impermiable layer of oxide on the surface to prevent further corrosion, so unless you have either a fretting motion that keeps destroying that oxide layer, or a chemical solution that does the same, it'll be fine.
Now on to important matters... NBH... hmmm... seems to me to be a technical term... whilst I seem to get the general vibe of the thing, the precise meaning evades me... let me guess...
no hope?
no help?
not hardly?
Ahh! By Jan, I think I've got it! Not Happy!!!! (Jan)
Best to be specific about these things!
Al.