After the rebuild and a replacement of the oil pressure sensor the noise was back with a vengeance, but as before it suddenly went and didn't come back again when I started it warm. As explained in the oil pressure sensor thread, the oil can drain back when this is replaced so confirms my thought of oil starvation somewhere.
I've read on here somewhere how to replace the oil feed pipes but can't find the post. Does anyone know where it is? I've searched for what I believe to be the obvious.
Btw I've seen an excellent video of starting the engine and bypassing the oil accumulator with a clear hose. This shows the oil being pumped from the left hand side to the right(sitting in the car). Therefore the accumulator must be there to lubricate only the right hand head at startup as it will need to go against the flow to lubricate the left.