I am not absolutely sure what the front springs are. When I bought the car I am pretty sure that Denny said that they were from a 351 car. It sat a little high in the front and I cut half a coil off them which got the height just about right. I have about 1" of downtravel at rest, perhaps a touch less. Remember, I have a 750 lb chunk of cast iron sitting in there
. I gotta believe that the Boss 351 is 150 lbs less than that.