I replaced those hoses on my K4. They ripped like yours, and new ones were cheap.
I think Bill has the right idea. If you look at the service manual, it shows a cutaway of the gas tank, and where those tubes go inside the tank. IIRC one is a breather, and one is the aforementioned overflow. They both have real thin metal pipes that run up inside the tank towards the gas cap.
Either they corroded through, or maybe did you ever drop anything inside the gas tank you had to fish out? Or clean out the tank by putting bolts in there with a rust removing agent? Both those things could have caused damage to those little pipes.
Might just need a new tank, repairing a tank is usually very cost and time consuming, find a used one.
Or, if it's infact the overflow line that is the leaking one for sure, you could just plug the outlet on the bottom of the tank, and not ever overfill the tank, or let rain dry out around the gas cap before opening it every time. If its the breather line though, you absolutely cannot plug that one up, it is required for the tank to work normally. If it's the former, it could still work, or would probably make a great track tank.
Hope this helps.