I've got SS bolts from Lowes in the fan mounting points on the radiator. They are M6 1mm pitch. Essentially all of the bolts which require a 10mm wrench are M6 1mm pitch. I've replaced most bolts in the engine bay with SS. Essentially all of the bolts which require a 12mm wrench are M8 1.25mm pitch. Hardware store M8 bolts will take a 13mm wrench. That covers all of the cosmetic type bolts (OEM bolt with 4 on head). If the OEM bolt has 7, 9.8, or 10.9 on the head, it takes a significant structural load. Don't replace those with SS. SS is actually pretty weak mechanically. If you demand a greater variety of bolts than the hardware store can provide, try http://www.mcmaster.com. They are my go-to source for anything weird.

Corbin
'97 GSX dressed like a '95 ESi