The roll of a stock Miglia bonnet can fight against you a bit when you are trying to hinge it ...If you look at the picture a piece of wood has been bonded on the bonnet and under the body to enable the hinges to be mounted parallel to each other and operate in the same plane , rather than against each other ...
You can make this a bit easier by joining the two hinges together , like this but obviously wider apart ...
note also , that the hinge pivot point is back about 50mm from the opening ...this will need a bit of trial and error working out ... but it gives you a starting point ...
Hinges are a right pain to sort out sometimes but look effortless once done ...