I found that the tensioner guide had worn a fairly deep groove where the chain feeds over the guide and onto the exhaust cam sprocket with minimal wear along the length of the guide.
The rubbing guide looked good... that was until I placed it against a brand new one, the original guide had a greater radius to it's arc, as if the tension of the chain combined with numourous heat cycles had "flattened" it out some... before removing it I had noticed that it was loose at the top, could be moved back and forth (in line with the chain... easy to check for with the chain removed) and tapping against the inside of the head... once installed, the new rubbing guide fit firmly snug... might explain the rattle, it was the fix for mine.