Guy,s with a B Body rear end...Questions
Hey Jim, although I don't have a 68 Barracuda, I did install one in my Dart Sport and I run a 60 series tire on a 10" wheel with 5.5 inch BS, works perfect.
I would think a 60 series tire would work with the correct BS. Install the rear, and do some measuring.
You may have to buy some new wheels.