Stay away from hardware store stainless steel all thread and stainless bolts from a hardware stores. Most of those are Grade 2 at best. If you want stainless studs call ARP.
ARP only has about 10% of what they manufacture in the catalog, so if you don't see what you're after that doesn't mean they don't have it.
Also McMaster Carr is a very handy place to get most anything it takes to run a factory, so they too have lots of options.
McMaster-Carr
Tom