Froggy,
Most of the camshafts used on postwar Douggies were marked between the cam lobes to identify the type of cam fitted. Touring models had a cam marked with a 'T', sports machines were marked up with an 'S'. The situation is not quite so clear with the Plus cams. Original Plus cams had a narrow groove machined around the flange that butts up to the front camshaft bush. From what I am lead to believe, the first cam (later referred to as the number 1 cam) may not have had any marking. The number 2 cam had a very harsh profile which the followers had trouble staying in contact with - even with triple valve springs. The later number 3 cam was marked with a '3' and was more like a high lift 'S' cam. As you say, early cams (nos. 1 and 2) should have .025" tappet clearance whereas the number three cam ran with .010" clearance.
Hope some of this helps,
Regards,
Eddie.