It sounds like it's getting better, but maybe you have a misfire. Is it coming and going, or perfectly regular? Even just off idle. ( get someone to pedal it) possibly the injector loom is not quite clipped on over 1 or 2 injectors, but I wonder if the original cam sensors could be replaced, to see if you still have same fault. They screw/plug in easily in 10 mins. You might get some other codes, revving it, like o2 bank 1/2 when they start sensing unburnt fuel etc.
You can buy a cheap fuel pressure gauge on say eBay, for about £25 you need to know what the pressure should be as well. Can't remember right now.
Shame, you have done a big job, and it's so nearly finished, and the moment is near to show a finished car.

I have also done the same job. (Chains etc) I had a couple of the sensor cables mis plugged. I think they were near the thermostat, and throttle butterfly. It ran, but was whining. Some plugs are the same! You can peel back the wire shrouds to see the colours, and reference them to the workshop manual wiring diagrams. Some of these sensors are too long, so they reach where they shouldn't
The tapping could be a lazy tappet! And will clear when revs brought up to 1500-2000 and held for a minute. But I would be thinking of sorting the fuelling issue before you go overevving, and overloading the 02 sensors with neat fuel.
There was thread a few months back with a guy with noisy chain, after changing it. and he had some misfiring I think. I advised him too to check the connections.

In the absence of Range Rover specific diagnostics it may be worth checking the conditions of each spark plug to see if there is any difference in colour between them