Comp vs Lunati

FWIW, I add a few hundred RPM or so to the bottom end RPM numbers for every common cam brand except for Crane.

The Comp looks to be an older style lobe without aggressive ramps, so would be easier on break-in and easier on the valvetrain in general, and you could probably get by with a softer valve springs since the valvetrain accelerations are lower. I would expect it to be a bit softer on the bottom end torque; I suspect your friend with that cam is benefitting from the extra cubes in his 408.

The Lunati should be a just a hair torquier at low RPM's based mostly on the LSA, and also on slightly smaller .050" duration, and slightly shorter advertised duration (265* for the Lunati vs. 268* for the Comp Magnum). It has more aggressive ramps and makes up for a bit smaller duration and wider LSA with higher lift for overall breathing, so the top end RPM ought to be close. The faster ramps makes the valvetrain more critical, and should call for more care in break-in.