Bluedog. Did you give KCM the info for the motor you wanted? Did you tell them what you where going to do with the car? KCM sells many hydro roller cams from .700" lift to under .550". You have not given any specs on the motor so it is hard to give you an idea or answer about your question. I have a 452 that is getting a cam swap right now. I got a KCM cam with .568 & 588 lifter. I am looking for alot of tork with a 6500 rpm limit. If you want every last HP out of a motor and spin it to 7,500 rpm GO BIG and live with the idle and some of the drivabilities that go with large cams. The smaller the cam, the easier it is on the motor and valve train. You want to have the tork power band at about 500 rpm into it. This will stop the car from lugging at highway speeds. Bigger is no always better on the street. Racing that's another story. I have a 368 hp motor with 446 of tork, 9.2 compression, shelby heads and block. Car idles smooth, pulls like a tractor to 5,800 rpm, ( I installed beehive springs on the shelby heads and added an Aluminium flywheel to add rpm before the motor goes flat and is out of power) I run 12.5 in the 1/4 mile and can run regular gas of 87.I have and FI system on the car also. A 500 hp motor and 550 ft of torque is a nice motor for a cobra. If you are racing, there is about 10% of the cobra owners that have MASTERED the driving skills, and drive a cobra to it's limit. This is a whole different subject.
Rick Lake