It might help if you could supply more info or pictures. How much of a restoration is in progress?
A good start to see what similar cars are on the market for is to have a look at sites like www.autotrader.co.uk or even e-bay bearing in mind that the asking price is usually not what they sell for.
Hi 1955 300b/186-011
needs full restoration feeling a bit nervous needs cash spending but optimistic!