Well after a bit of jiggery pokery all seems to be working well, AVL engine is now breathing via our hosts oil tank tower extension, I can feel it through the rubber pipes pulsing in and out and rear chain is getting a very slight oil mist, much tider and all old gubbins removed, also oil tank level is now at middle of the dipstick and it appears to be staying in the oil tank, so happy days!
One problem I did have was a bad oil leak via the gasket on the tappet cover (right mess) , tried two separate new gaskets with grease and then Wellseal but just really leaking. Measured the gasket thickness and was around 1.6mm, recovered the old black one that was on it (poss OEM) and it is 2.5mm, put it back on dry and no oil leak! I think the stud that holds the cover has too short a threaded length so the gasket is pushed too tight against the shoulder, i could see a very pronounced hexagon shape pushed into the gasket meaning I am just crushing the gasket in the centre and leaving the edges loose, think he shaft needs the shoulder turning down a bit to allow the nut to pull it up fully and tighten as the gasket crushes and not before, of course works fine with the thicker gasket as the centre sand edge crush points are equal.
However, I seem to have lost compression