the first fault was due to some dumb ass fitting the injector clamp without the little top hat.

there doesn't seem to be any sign of it running too low on oil. ie shells are fine although im changing them for good measure. cam shafts are fine, no blueing and there well within wear limits, (at last I got to use my micrometer in anger). no play in the mains or the small ends either. just the rings and pistons.

luckily iv got away with just honing the bores.

verdict
£280 new set of pistons with rings.
£35 new shells
£51 head gasket set
new oil filter, oil, anti freeze

fitting this weekend.