Skimmed the referenced guides; which are definitely worth the reads but surprised I did not see (admittedly might have missed) discussion of kind suffixes on constants; and trimming trailing white-space and expanding tabs which is easy to automate.
It is very easy in standard free-format Fortran (although preprocessor directives can complicate things) to extract comments from code and run them through spell-checkers and review them (as mentioned very nicely comments are not checked by the compiler so are prone to accumulated errors);
I know of strong camps over whether variables should be declared only one per line or in tightly related groups versus minimizing the number of declarations. In either case asking people to look at their variable names and changing them to be self-describing if appropriate can be useful.
Often the compiler can flag unused variables, which are almost always something to remove.
As mentioned, if the compiler writers took the time to produce a warning message about something it is almost always worth considering eliminating.
Did not see order and grouping of variable declarations – locally most preferred is parameters first in order declared in the procedure declaration unless required by the compiler to be in a different order; and then local variables first by type and then alphabetically seems to be the most popular style locally.
So if those are really not in the referenced guides that is a few more that can generate interesting discussions. Some actually can affect results such as constant prefixes so many od those are not considered as just “style” preferences (?)