Sounds fine to me aside from the valve clatter. Get those puppies back in spec and then see how it sounds with the clutch cover off. I would be willing to bet the "piston slap" gets louder.. Lol. Sounds more like stock clutch noise than piston slap. Try the old screwdriver to your ear pressed against the engine trick to see if you can hear anything better that way.
Thanks No Fly Zone. In terms of adjusting the valves im able to remove the front valve cover fairly easily, but im having trouble removing the rear valve cover as it hits the frame when trying to pull it out.
Flakes of metal on an oil filter is never a good thing. You need to find out whats going on... if its "flakes" I would say rod bearing. If its shiny dust it could be a few different things.
Pretty sure its not a rod bearing because it would get seriously worse when you revved it.