Just have a look on ebay. It doesn't have to be a Mocal one, any 13 row cooler will do - they are not G40 specific. Easily get a new one for under £40 delivered. Just look for the MGB ones, there's loads available.
As for the take off plate, get one with a built in thermostat. Hoses can be made to suit by many different suppliers or you can make your own with parts from Rally Design etc.
Avoid the so called specific kits, they are normally very expensive and the hose lengths aren't very "specific".