I poured the concrete. I used that quick drying stuff and it's pretty dry when mixed to the manufacturers specs ... didn't like it! Anyway, it's done! I left a space for an over the pipe closet flange ... just in case.
Also, I replaced the fittings on the stack to delete the washer trap and turned the sanitary tee to run the drain. It's 1-1/2", so I hope that'll be sufficient for the drain.