Olev, the timing side bearing journal is also larger and, of course, the drive side shaft is longer to accept the alternator on the A65/A50 crank. The drive end can certainly be modified on a lathe, or you could use this as an opportunity to add an alternator. Then, of course you'd have to put a cush center on the clutch because the cush drive is gone. The timing side is even more problematic, and I haven't quite figured out how to deal with that one. There really isn't enough meat on the case to install a the larger bearing, so I'm leaning toward welding in some material to support the larger bearing. I don't think grinding the journal diameter down is a good idea because it would bring the oil passage dangerously close to the intersection of the cheek and the journal.
So, while I think it can be done (and I plan on doing it for my A7 racer), it's not as straightforward as first impressions would have you think. For a street bike, I don't think it's worth the effort.