If it is worth it to you, it is worth it. I have an old bike boom Takara, and while I don't have a fortune in it, I probably have more than I could sell it for invested in it. But I'm not selling it. I'm riding it and the bike makes me happy for reasons many wouldn't understand. If you dig this bike and you want to do what you want with it, that is your business not any internet stranger's.
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"It is the unknown around the corner that turns my wheels." -- Heinz Stücke