Cam card specs meaning

The differences you are seeing are the ramp speeds for the most part. The Hughes and Lunati use a very fast ramp, the Comps (even as an XE with the ".904" lifter profile lobes) are not as quick. So you see them starting to open later and close earlier. I am of the opinioin that there is a limimt to "too fast" for street cars, and i tend to stay away from rates of lift that are that fast because of idle time and oil issues. Of the three, the Hughes looks "the best". However, for a 4" stroke engine, you can go at least 10° more in duration at .050 with no loss of streetability. Something like the 20-225-4 (XE284H, not the 285HL) would be a nice match for stock port Edelbrocks.
As for the springs... lift is not what you use to determine what is the right spring. Pressures are. The Edelbrock singles are an ok general purpose spring. Unfortunately, any modern fast rate lobe bigger than around 225°@.050 needs more seat and open pressure than the stock springs can take. So figure on replacing them with matched ones for whatever cam you choose. A savvy machinist can usually find a part numebr for an inner spring that when used with Edelbrock's outer is perfect, for less money and you can re-use the Edelbrock retainers. Otherwise they will need to make sure th Edelbrock retainers work with the choice of dual spring. Also, any dual spring needs to be installed without the inner spring for the camshaft break in period. Otherwise you will very likely wipe off a few lobes. So when you do have the heads setup, remind them of that.