Solid cam questions.

On milling the head for comp ratio increase, it's a fine way. Though you should have built it that way first, your now spending extra money to adjust your plan. Thus the saying, "Make a plan and stick to it." Because if you don't, it will allways cost more.

Cams work in compresion ratio ranges. When there not in the range or intended useage as well, things go bad.
At a 9.0-1 ratio, you can still make decnt power. More compresion, more torque.
So if you mill the heads, remember this also moves the valves that much closer to the piston.