Using small strips of card I "gapped" the bonnet by sitting it in the opening and wedging pieces of card along the sides to centralise it. Once centred I measured the drop in height between the bonnet and the surround and made some spacers, again out of pieces of card to sit in the aperture and raise the bonnet to the correct height. After a few last minute tweeks I attached the bonnet hinges to the body through the radiator opening and swung the hinges up to meet the underside of the bonnet to gauge how much fettling would be required to get them to fit. Unfortunately, quite a bit... I decided that the best approach would be to re-weld the hinge plates to the arms and set about cutting them off.
Once removed I fitted the plates to the bonnet and the hinge arms to the body, I then swung the arms up to meet the plates and held them in place with a few tack welds. Once it had cooled down, I removed the hinge, made a permanent job of the welds on the bench and re-fitted.
Voila, perfectly fitted hinges with a perfectly centred and height adjusted bonnet
