One thing to keep in mind is it is easy to find ' Whitworth' threads even stainless, but they are usually UNC. 'Same' bolt, but different hex.
There's really mainly 5/16"BSC to deal with, so nuts are easy; only a few 1/4", 3/8"and a couple of 7/16"BSC to deal with.
7/16"BSC can be done with UNF, but the hex (and maybe thread form) are different (as with all Unified threads UNF/UNC)