Definitely agree with doing more homework. Dont just assume the tire is rubbing because of subframe alignment. Measure at the proper points. It could be another problem.

Amervo, alot of that info is already available online, so dont go ruining your binder for it

http://www.1968firebird.org/68sm/frmt/frmt6.jpg
that is from a '68 manual, but the measurements and diagram appear the same.

I still think if you kept the rear fenderbolts tight it would not change the sheet metal at the doors much, but it would definitely affect bumper alignment.