I highly recommend the Enthoo Pro chassis linked above. I just put one of the Supermicro + boards into one. About 1/3 of the holes don’t have match up with standoffs (I used non-conductive spacers instead where there was metal underneath them to support the board).
If you want pictures, my build is documented at My new SNAFU build - 'Turbojet' - #2 by talorgen. I’ve built other PCs before, but this was the first time with a non-standard board size.