In my opinion, ( and I happen to know quite a lot about the design of that particular rocker,long story) , I would stay at the no more than, 600-650# range. Crane Golds ( as noted, they were " designed" for 600#) served a purpose, just as these rockers serve a purpose, but they weren't meant to replace a set of rockers designed for large , or bigger roller cams. Everything has a limit. "Hoping" that a lesser designed product will work for a larger designed application is a flaw in strategy....lol...and there will ALWAYS be a couple applications, where people have done this, and done that, and get away with it. What you DONT hear, is when it fails. No one wants to admit that usually. When it fails, it often takes other valuable components with it. Those stories are often kept silent. So, can you? Sure. Good idea? Perhaps not. For the record, the Harland Rockers ARE extrusions, and then go thru a process of deburring etc, as most extrusions due, to limit stress risers and well, to make them look nicer.