Wayne, If your installing a cam better put some rods in it. I would also look around at the differnent cam places to see what is out there. There are more options than Precision for a command cam. Vogel MFG, super cub, Hackman, Web cams in california will do anything you want to a cam. I know stock heads will take around a .440 lift cam. The roller rocker setup is real nice. It is in my stepdads ch18 along with a hackman cam and supercub bottom end. As Caseracer said the cylinder heads hide a lot of HP. We just got a set back from having a bunch of work done to them and it made a very nice difference in the way the engine performed. My own opinion from using the adjustable pushrods, there junk. Figure out your correct needed length and get some proper one piece ones. There are some nice cam grinds out that use stock rockers with a set of high performance hyd lifters and run with the stock rocker hold downs.