Cabbie, A good stock 235 head is around 7.5:1 and an "848" head is around 8.0:1. Either head can be selectively milled, but will require recessing the valves. If you find that your dirty "848" head checks out ok, just have it surfaced milled...no valve recessing needed... and you'll have 8.0 to 8.2 compression ratio. Perfect for the street.
