That chart is worth saving. Never have heard of this alloy 20 stainless. probably, titanium is what the highest level guys use with carbon.
Mostly, all my s.s. rusts a little already, and i hadn't noticed that the bolts in the carbon were any more rusty than usual.
You can make your own cheek block and fasten it with epoxy and carbon using an existing sheeve. My policy is; getting rid of as much metal as possible is the way to go.