Hi Hugh
The scale is odd in imperial it is 3/4in to the foot, it would be easier to convert into metric especially as the real ship dimensions are in metric this works out at a scale of approx 80:1 i.e 1m to every 80m
The problem being that your hull length and beam don’t correspond to the full size version so you will have to make a lot of compromises as the hull works out to a 70:1 beam but a 90:1 length.
To be exact to 80:1 you would have to create a specific scale rule as it is an odd size.
Hope this is of some help and good luck.
Paul