IIRC there's a MinGW non-Cygwin build of bash

Sounds like you're thinking of msys, and it comes with 'cat' ... but not 'rev'.
Even my Cygwin shell does not provide 'rev' (though it may be available for separate download).

If you're just going to use 'cat' to spit out the contents of a file, you can use 'type' instead in cmd.exe shell:

C:\_32>type /?
Displays the contents of a text file or files.

TYPE [drive:][path]filename

C:\_32>
[download]

I don't know of any windows built-in equivalent for 'rev'.

Cheers,
Rob