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Sheldon Brown has a crib sheet on the relevant distances https://www.sheldonbrown.com/cribsheet-bcd.html
If it is 151 it will be the older version of the cranks http://velobase.com/ViewComponent.aspx?ID=cfcf4483-7a67-4f81-86bf-e6667fe2f57d&Enum=115.
This could make it more sought after than 144 but the other side of that is the chain rings are probably harder to come by. I don't know if this would also impact on the BB spindle size.The other issue is that they are 170 and a lot of people would want 165 but anyway they would probably make around a £100.
Recent ebay completed sales would give you an up to date idea of current prices.
Are they 144 or 151 bcd ? This could impact on the price.