McMaster Carr (mcmaster.com). You can order just about any fastener in all sorts of grades, both metric and standard. They won't be factory spec TTY bolts, but you can torque them as needed to achieve the same clamping force.
Also, you should generally avoid stainless steel fasteners unless the corrosion resistance is the first concern. Stainless steel is usually more brittle than standard steel and will break or crack in ways that a normal bolt won't.
04 Pontiac GTO
400+ RWHP / 400+ RWTQ of Magnacharged goodness --- Flowmaster cat-back exhaust
Pedders Track II with Hotchkis swaybars --- 06 GTO brakes with stainless lines and Hawk pads
10-speaker, 1200-watt custom sound system
98 Pontiac Grand Prix GTP