I think I'm having a bit of the same problem, except my engine is a completely rebuilt 20r using engnbldr parts and the new RV cam. It started out as what I thought was purely valvetrain noise, but I've slowly got myself convinced that the valvetrain noise is not excessive. I've got an exhaust leak to fix tonight, I'm hoping it is part of what I'm hearing, but I don't think so. My timing is adjusted to ~2.5*btdc down from 5*bdtc, retarding it helped a little. I'll be interested in what you find out.