What gcc warnings are useful when looking for LP64 botches in code?

I'm using this:
CFLAGS+= -Wall -pedantic -Wmissing-prototypes -Wmissing-declarations \
         -Wpointer-arith -Wcast-qual -Wconversion -Wstrict-prototypes \
         -Wredundant-decls -Wnested-externs -Winline

Is this overkill? I'm ending up with thousands apon thousands of
warnings. (Ok, 90% of them are redeclarations of errno, "but still!")

Thanks.
-- 
XCOMM Kevin P. Neal:  Senior, CSC, NCSU    http://www.pobox.com/~kpn/
XCOMM 
XCOMM "There are %d threatening little dwarves in the room with you."
XCOMM    -- BSD /usr/games/adventure source code.