Anyone ever use on of the CompCams ductile iron roller cams? I am looking at the 212/212 roller and already have my GM roller lifters. Springs will be from CompCams. I need to know how they work out and how they are "retained" in the block or if they just use the stock type button and spring in the front like stock. I am looking into that because the billet setup being $1200 is a little steep right now and I am trying to start on the car by the end of this month. All I am lacking to really get this project going is the turbo that the post office probably lost, the camshaft, and my torque converter.