I added an 848 head in place of the 55.2 head (don't know the casting #). I noticed two things: better fuel economy, more torque. It was noticeable on the road. I will admit that the intake valves on the original head had recessed into their seats to the point where I'd run out of adjustment on the rockers. Hence the change of heads. I'd calculated the CR to be about 6.8:1. So bumping to 8 was a significant upgrade.
