widest tire with spring relocation

I have a 67 dart and the widest tire I can fit is a 255/60r15. just want to know if I can fit a 275/60r15 if I relocate the springs only without mini tubbing it. if I mini tub it I will want to narrow the axle, I may do it later but at least maybe get a wider tire under it for now. any knowledge will be appreciated. thanks