All you did was lower the rating of the bolts. Your grade 8s are now somewhere between an 8 and a 5. Anytime you heat a bolt you affect the factory heat treating to some degree.
Fastenal? Why? You can get most of what you are looking for from the specialty bins at Lowes, Home Depot, Ace and True Value. Add in some side trips to Auto Zone, DAP, CSK, NAPA or CarQuest and you will have it all, in stainless, to and including brake bleeder screws. Most available single or 4 piece blister packs.
The only place you need hardened bolts is the shock mounting and in the engine. Shock bolts should be grade 5, not grade 8, you need torsional strength, and 8s can snap pretty quick under side loading. Even fullsize truck IFS systems mount with grade 5 from the factory.
Push come to shove, check out the online catalog for A.R.P., they sell stainless fasteners in the 190,000 psi break/stretch strength range. That is there standard, you can get stronger if you want to spend the extra change.