just went and compared the top clamps from a k6 and an f2. the f has about 1/2" less offset from the stering stem, bringing the tubes closer to the tank in that way. also, the pinch bolts are in about the same position, but the angle of the cut is different. the k is anged about 15 degrees more forward than the f. which would make the bars come back even more with the lesser angle of the f clamp.
i dont know if these two differences add up to enough extra clearance to make it work, but that is all i could see.