You want these http://motorbicycling.com/f23/beefed...0-a-18927.html I got them before they were being offered heavy duty borderline OK for a bicycle but destined to fail. I got them done up by SportsCarPat and now I feel quite comfortable knowing they will hold up to the stress of aa motorbike. Do Yourself a favor spend the extra money up front if You dont you will wish you did later. VeniceMotorBikes sells them as well as SportsCarPat both members here.
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I'm not sure a vintage one is any better. I have one from a spiegel airman that is bent on the steering tube. There is one on ebay with the exact same bent tube and stripped threads. The welding is better but the steel used in those old tubes might be lighter.
or maybe there just can't be expected to last 60 years.