A well-fed dove stamped into the steerer tube is Columbus' signature; “spinner” doesn't mean anything to me. I think that Columbus rifled the steerer tubes on several different tubesets. If the seat tube has rifling at the lower (thicker) end -- should be able to feel it, or see with flashlight -- then that means the seat tube is SLX tubing. But the bike could be SL as well (earlier), or some later tubeset, considering the arrowhead lugs and vertical rear dropouts. 1962 g is quite light for the frame only. I have a couple Columbus frames, of somewhat larger size, that weigh in the 2000-2100 range. You've done very well!