Awesome! I have several 904s out there with 500hp+ that work very well.
Keeping on theme with the original intent of this thread, yes, I would absolutely encourage folks to use a 904 behind a small block. They are lighter and quicker as we all know.
With that said here's a car we put together several years back that was originally a slant 6, 3 speed manual, 8 1/4 car. We installed a 340/904/8.75" and it worked very well.