I've only heard of the 4-7 swap cam for Chevy engines, supposedly increases and smooths out the torque curve for those running 1/4 mile shots. Don't know if there is any benefit on the street.

Just as an aside, 2.56 seems like a pretty tall gear for an 200-4R overdrive. I have 3.55 in mine with 245-60 15 rear tires, and run around 2200 rpm at 70 mph.