I think this has been covered but a quick search didn't give me the answer I was looking for.
tapping some SS screws into aluminum (mast base blocks on the 31). I really don't anticipate having to undo these anytime remotely soon (previous blocks were bent and I had to basically torque the heads off the previous screws, grind down, re-tap) but thought I might try to at least preserve the options. 4 #10-31 screws ought to keep things solid too. I saw some people mention physical isolation but that isn't practicle in this situation.
spray stuff corosion inhibitor?? how long would this reasonably last? the previous blocks were there for 10 yrs so I figure it might be that long again. I don't think it is reasonable to think that spray on stuff would last that long so I might just forgeeeetttaboutit.

Use this and you will be able to remove the screws 10 years later.

Google TEF GEL

thanks... I think I will try that.

Tef gel is the best. I think APS and Layline carry it.

Two things to consider. If you want to do screws, and what you're screwing into may not be too thick, consider these:

Rivnuts

For corrosion protection, we've also had good luck using:

Lanocote

+1 for Tef Gel.. expensive but worth every penny but you shouldn't need all that much anyways.