Solid cam questions.

How did you know ahead of time that the cam would have enough piston to valve clearance? I want to get a new cam but I don't want to buy one and go ooooooops. I don't really have enough compression right now for a roller. (only going to be 9.1:1 with the new Edelbrocks) But what do you think about milling 10 cc' s out of them to get 10.1. Is the increase in compression worth the cut? (factory said they're good to cut up to .060... this cut will take .040.