I have used mostly steel Grade 5 and some Grade 8 on my restoration. As to stainless, that would be overkill for my truck. Maybe perfect for yours - your call.
What I can recommend is that you buy a stock of Bolts, Nuts, and Lock Washers. Most of mine are grade 5. You will mainly need 1/4", 5/16", and 3/8" from 3/4" long to 2". Buy them in bulk - at least 25 count bags to keep the cost low. 40-50 year old lock washers and rusted bolts are not worth the time to mess with.
Paul
