You could try contacting The Fastener Engineering and Research Association. Data files 5 and 6 are extremely helpful for selecting stainless steel fasteners.
http://www.fera.org.uk/
Regards, Nuno.
Going back to MintJulep's original question:
"It is important that the stiffness of the members be large compared to the stiffness of the bolt."
This refers to the risk of relaxation and embedment, from my experience unavoidable, could be up to 10% of clamp load for the first 24h, a...