Tire sizes w/ spring relo kit

Did a little searching throughout the threads and haven't seemed to be able to find a good answer.

Doing a spring relocation kit on my 70 dart at the moment, and am trying to figure out what my options on tire sizes are.

Does anyone have a clear answer on how big of a tire you will be able to fit with minimal work after a spring relocation kit? I plan on running my factory rally wheels, but wouldn't mind switching it up to be able to fit more tire with a different back spacing. What have you guys experienced with any of this?

Mini tub is not out of the question, just not sure if I am brave enough to tackle it yet.

Give me some options guys.

Thanks in advance