My buddy has it in his 347. It sounds awesome at idle, and despite what comp says, he runs it without any computer mods. It likes to rev, but as far as power, I can't really say. His car is more of a cruiser with all weather tires. It just blows them off.
From reading up in the XFI cams, they trade low end torque for high end HP. Although, on a 408 you probably wouldn't notice.
It can be a good cam for a 408 depending on the exact combo. I did a custom profile that isn't too different from it and made great numbers....very street able as well.