If you try 225/60/15 check the distance to the front bottom wheel lip turning the tires to the closest point. Should be 3/4" clearance. If not fold in lip or try positioning the lower fender support brace out for more clearance.
Moving the lower fender brace will be hard on a Barracuda sense they have a lower valence that bolts onto the front lower fender. That makes thing more ridid. On my 68 Dart, with no valence, I drilled new support holes on the lower fender and pulled it out a bunch. Looks fine, but if I mention it to someone they can notice it's flared out down there.
I run 245/50/15 tires now on 15x8 rallyes. That works great. But that size is eliminated in popular brands and street compounds. Avon, Mickey Thompson might make something like it.
