Sorry to keep only reporting back with bits and pieces, just been really short on time lately.

I should be able to get around to checking all the lash on the 'bad' side today and also check the roller tips too. The pushrods flexing sounds plausible too, but like Madscientist said, why it would only happen on one bank beats the hell out of me.

I did get a chance to cut the filter open. Please excuse it being mangled, ran out of die grinder wheels, couldn't find my tin snips and thought using an air chisel would be a good idea LOL.

The oil that came out of the filter was a bit gray but didn't really have any metal sheen to it when rubbing it between the fingers. I couldn't find any metal dust, flakes or anything in the filter upon inspection. I even blew it out with brake cleaner into a clear plastic pan and there was nothing (the metal flakes towards the top of the pan there I believe are from the filter and my air chisel job, you can see the orange paint on them).

Keep in mind, this oil probably has less than 500 miles on it, not sure exactly since I still haven't had a chance to order a new speedo gear. The motor itself probably has under 2k miles on it.

When I did the first oil change after break in there was a tiny amount of metal dust on the magnetic drain plug but didn't look excessive for a new motor. I never checked the filter, probably should have.

540 duster, I noticed a difference on a few even the last time I adjusted it with the adjuster being at different heights after setting lash. I notice one on the "good" side where I couldn't get a shallow socket on to do my final torque check whereas all the others I could. I'm thinking I might buy all new adjusters for the hell of it. One was frozen up pretty bad as well.