Guy,s with a B Body rear end...Questions

I have a 68 Barracuda and I am thinking about putting a 1965-67 B Body rear end under it. I will be running 15'' tires.Can I run a 275x60x15 tire with the B Body rear end.If so what backspacing rim would I need? I don't want any rubbing issues? If I can't run that big of tire how big of tire can I use?
I have torque thrust with 3 3/4 backspacing ,but imagine I couldn't use a very wide tire. Any idea on how wide of a tire I could use with the torque thrust wheels?

Thanks,Jim