From an insurance point of view the bike would be a write off due to the cost of frame repair. It only the top tube needs to be replaced... well I don't know way $100-200 and then $250-500 for paint? The frame itself while decent quality is worth say $100-150 maybe. There are no hard and fast guidelines and everyone will give you a different estimate. But to get a bike of similar quality by todays standard (extrapolating the fact that this was a good bike then) you'd be looking at close to $2000.