Hmmmm. Guess it's too late to say the front of the body should be cross braced and secured to a fixture of some type before cutting out the old firewall.....

Measure everything at least twice, and tack from the center out.... Works good to have another pair of hands around and hammer weld the spot welds as you go.. If everything is not square with the cowl and firewall, getting the rest of the front end together is going to be a nightmare!!!!