Frame is indeed a W/NG one, both field stand swivel point and spring clip brackets are partially there.
Rear fork end points down, that is also a giveaway for a W/NG frame.
But nothing wrong with that, pretty normal to use such a frame for a competition bike.
Magnesium crankcase is da pukka stuff, but after so many years very likely to have loose mainbearings .
That can be solved by making steel inserts for the bearings.
Song for Adrie : https://www.youtube.com/watch?v=0CFuCYNx-1g