ANYONE RUNNING A COMP CAM XE262 IN A 340?

You can retard it, but I would only retard it as far as I needed to center the overlap triangle. No more.
That's above my pay grade. A local friend suggested doing this to get a later intake closing event (unfortunately, probably a later intake opening event as well) to bleed off some of the dynamic compression. I'm affraid that I am not well versed in cam science, although I do enjoy reading cam threads.