Right let me try to answer as many questions as I can and btw thanks for all your advice.
Since it was rebuilt I have had it totally apart twice trying to cure this problem. Both times I have replaced the check valve behind the oil pump just in case. The TMS pistons cured the smoking problem not caused it the old pistons caused it.
I do not have an external oil filter fitted.
The oil has never failed to circulate that I know of and I check it every time before I ride it (yes I am paranoid about this bike lol)
I do not have a magntic sump fitted I took the cheap option and welded a nut inside the sump cover to give me a drain valve and no it is not hitting the gauze.
The gauze is perfectly clean. The pickup in the sump checks out completely no leaks or cracks.
Now for the latest developments. After throwing all its oil out and virtually draining the tank I took the seat off (yes it was full of oil under there as well) covered the bike in foam gunk and attacked it with the pressure washer. At least that got rid of the oil :)
I topped up the tank with my normal Morris straight 40w and waited for it to do it all again. 200 miles later (140 0f them in the same day) it has shown no sign whatsoever of pumping any oil out???????? The only difference being that I never went above 55 mph.
Now IMO the only thing that causes oil out of the breather like that is excess oil in the sump. Faulty scavenge has to be the problem IMO. If its speed related (when it happened I had been cruising at 65/70) then again IMO all it can be is the oil pump. Thats my theory anyway so if it happens again I will change the oil pump and see where that takes me.
On the plus side barring a slightly dragging clutch (yes the whole thing is new including the bearings, 4 spring type) the bike is a pure pleasure to ride and it does not smoke :):):)
Today, after my 140 miles I fully realised exactly why I fell in love with A10's 45 years ago whether I will feel the same the next time it covers me in oil I dont know