Last post to wrap up the thread which had it's ups and downs but has been ultimately worth while.
Engine has settled down now, very quiet and soft if that makes sense, absolute pleasure to drive - added bonus the oil level light now works too, no idea why changing the head would make a difference but it extinguishes as normal.
Other bonus parts, higher capacity alternator and improved fuel heater with large inlet bore, no more air -
Internals, you get the added benefit high temperature kryptonite exhaust valves, this may include the seats also (not checked).
Getting a replacement water pump housing sounds easy right, nope most of the second hand parts corrode around large hose connections - MB only do exchange units with the replacement needing some JB Weld to smooth out milled surface.
The other bonus is my lovely neigbours who helped lower the new head onto block, absolutely amazed the thing works let alone drives after being a pile of bits
(again)