I just finished up a restomod '52 3100. I usually use steel nuts and bolts for my builds, many of them original. This requires a lot of time on the wire wheel on a bench grinder (also known as a small parts dispenser), them wipe down with acetone, prime and paint.

"Since you live in the low deserts of AZ, why do you want to convert your hardware to stainless steel? Stainless bolts can be problematic, as they tend to gall when nuts are tightened on bolts, making them difficult to remove. I have torn 2 trucks down to bare frames, and found little difficulty with the standard factory bolts. One truck was from CA and the other SD, both well used trucks not protected from the elements."

Grade 5 hardware/original hardware is just fine. I reuse all I can. The only thing you can't reuse is lock washers if they have taken a set to flat.
SS (or as industry and military calls them, CRES)

, is great for phillips head (or as industry and the military calls them, cross recessed)

trim screws in cab.
It would be nice to buy Gr 5 black oxide hardware for an old truck. I don't like painting, it always seems to chip off. I guard original blackened hardware with my life. I try not to chase the threads, just wire wheel as Carl says.
I think broken sentences (with parenthetic info in between the structure) are hard to read. I don't do that either.