Thanks for all the replies guys. i not only had to use these checks on my spare case, but unfortunately on my recently rebuilt motor too.
basically i had frothy oil for some reason, did a few hundred miles on the rebuild and in that time the oil light flickered on for about 5 seconds maximum. it didnt happen again, so continued to use it for a couple of days, but thought i better strip and check just incase there was a problem...
Soooo, case split i found bearings and crank marked, enough to need a regrind!
such a big big shame as i had a std 2 litre crank with NOS vw bearings.. now i am having to use .25 mahle ones, which are no way near as good and belive it or not, i had to elongate an oil hole in one of the main bearings as it didnt line up properly...
anyway, to the cause of my problem...
I couldnt see anything wrong. anywhere.
Spoke to my friend Tom (wheelerdealer) and he suggested i check the oil pump to case clearance...
So with the left half of the case i fitted the oil pump and bolted it in, i did as Tom told me, shone a light down the oil feed galley from the oil filter housing back to the pump, and saw light between the gap on the inside of the case..