Degreeing the cam is especially important if you have the head milled for that extra compression as the shorter distance will retard the cam timing.

For compression I just want to add that the bore size has a lot to do with detonation and the small bores (say 3.189 compared to over 4") create fewer opportunity areas for pre ignition to begin. Also, look at the alum vs cast iron thing the other way; iron retains heat and so requires less compression than aluminum for the same amount of heat-power output. What I mean to say is that two identical heads with one made of iron and one aluminum, the iron head will make more power and the alum will require more compression to make the same power (heat/energy output). Aluminum is easier to machine and is much lighter which is why it is more commonly in use now.