Well, we spent the evening on EL_swervo's Omega in perfect working conditions. I wasn't looking forward to spending the evening in a works car park in this weather but I shouldn't have worried
Firstly we confirmed that the Laser tool didn't align with the water pump pulley so back to the seller for that I reckon. Fortunately mine fitted and on inspection cam 3 was a couple of teeth out and cam 4 was a good 3 teeth out (advanced, fortunately, which is the safe direction for an exhaust cam to be out). The tensioner was loose, barely off the stop and, whilst the belt clearly hadn't failed it was cracking up on the smooth side.
There were signs of a ham-fisted belt change previously. The cam belt cover was cracked and the rubber sealing strip was missing. The tensioners were as new. Given the condition of the belt this was surprising.
We fitted a new belt and tensioners and timed it up properly, put it all back together and started it. For a few heart stopping seconds it rattled like mad but then started to quieten down. It clearly wasn't misfiring so it was looking better then we feared. We then noticed an "oil lack" warning on the MID and, on inspection the oil level was low.
With the oil topped up we gave it another run and, after a second or two of rattling it quietened down and idled and revved very sweetly. A quick listen with a screwdriver to the ear revealed no unusual noises from the top end.
The original noise started when the car was on a hill so my suspicion is that the oil pickup sucked a little air due to the low level and that the noise was the lifters running on air. Whilst the cam belt was in poor condition and very badly timed it was odd that only cams 3 and 4 were out so I suspect that it may have been mistimed when it was fitted since the last person in there was clearly bit of a cowboy.
Anyway, I await a report on how it drives now. A little better then before with luck.
It was good to meet you, EL_swervo, and thanks for the all the tea and freebies
Kevin