My truck is a combination of your Vic and your F.
Not necessarily the positive parts......
No need for grade-8.
In fact the higher carbon and extreme work hardening tend to make a bolt that's more likely to rust, and deeper rust than normal.
The stress is not great.
You would probably be better off with grade 5.
I use stainless bolts on my exhaust manifolds (yes, I know this is the heated floor between manifolds)
So happy to have no corrosion and fully formed heads for wrenching on.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.