I made it out onto the drive today to get the engine up to temp. It did improve but still doesn't sound as smooth as it should. It sounds more like my M54 does for the first 3 seconds after start i.e. a bit of flutter prior to the lifters quietening down, but it just keeps on going. I let the engine come to 100 degrees and then sit there for about 45 minutes with some rev-ing now and again. Vid here
https://www.flickr.com/photos/58068042@N07/15383223135/
One of the nasty rattles I could hear that I thought was coming from the vanos turned out to be the water pump pulley screws working loose (about 1/2 a cm) which was slightly vexing. Once I'd identified that and tightened them up the rattles went but I was still left with the ticking and valve train noise which settled a bit over the hour.
I'm going to check the oil level again once cool and drained down and top up if necessary. I'll probably grab some of that Wynn's stuff Peter recommended tomorrow. I'm always a bit suspicious of these engine treatments but as the thing has done 150K it can't hurt to try.
I appear to have fitted the loudest rad fan in existence too. When that kicked in at ~95 degrees it drowned out all other noises which was a bit irritating. I struggled to get the oil over 80 degrees too, I believe it should be closer to 90-100.
One thing that was bothering me a bit was the oil pressure. I've never (unsurprisingly) owned a car with an oil pressure gauge so not sure what I should see. It sits at 1/2 a bar on tick over and then raises to about 2 bar when you rev to 3000 rpm but I never see it go higher. Is this correct behavior?