If you do not intend to 'invest'** time and money that you cannot recoup then a boat is not for you.
Whatever you do to it, it is still a 50 year old boat and you cannot change the shape or character of it.
As the inside is totally stripped out you will need to spend £000's to get it liveable (electrics, water, gas, heating, stove etc etc - that is not going to be an investment, it is going to be the cost of your enjoyment.
Unless it is being given away, or at a peppercorn price, then whatever you spend is likely to be written off, a 50+ year old boat has a price ceiling irresepctive of the 'gold plated taps and jacuzzi'.
Does it have an engine ? If so what type, condition, etc etc.
** Investment : put (money) into financial schemes, shares, property, or a commercial venture with the expectation of achieving a profit: