This is the second set of Nervex lugs to be presented in this crazy way in the last ten days. The first set did not sell for big money from what I recall.
I have never tried grinding out the ends of tubes and would imagine that the mitred end of the down-tube and that of the top-tube where they enter the head lugs would be enormously tricky and time consuming; Imagine poking about inside the lugs just trying to get into the crevices with a Dremel tool.Ugghh!
The way this sort of dismantling used to be done was with a great big soft flame such as that from a town-gas /compressed air torch. The whole joint could be raised to the melting point of the brazing spelter without any danger of burning or overgheating the steel. Nervex lugs might well be quite thick, but bits can be pulled off..like the front twirls and those little spikes at the cheeks..if the metal is not quite hot enough.
Norris Lockley
Settle UK