I looked into this a few years ago. You are right about the bolt pattern-so no the drums don't bolt on. Also they are 11x2-1/2 on rear so backing plates don't bolt up. Axles do not interchange and the entire rear is different. In front the spindles will bolt to the bird upper a-arm & ball joint but the lower is different and none of the big car stuff works on the bird. It could be done but would require much fabrication & modification. Pontiac did consider these for GTO and built a prototype but did not produce them. Several years ago there was an article by a guy who did the conversion. The result was great but VERY costly and time consuming.
Brian 67 Bird Convrt. under construction, 67 Tempest 428 Covrt. finished(?)-owned 35 yrs.