What headers are they? What chassis were they made for originally? Reason I ask is that they need to be made for an Early Bronco or you're going to have headaches with clutch linkage on the driver's side and frame and/or firewall clearance on the passenger.
Like he said though, basically the heads are the same bolt pattern and similar, if not exactly, the same port size. So you're good to go there. Just be sure they're rated to fit in your chassis first, and with a lower height than they were originally designed for too. Since the 302 is shorter than the 351 they were slated for, that lower height might make a difference too.
Just curious, are they shorties or longies? Bronco or other?
Paul