70' Chevelle largest rear tire/wheel combo ????

[Nick.V70]

What have people seen or done on a 70-72 Chevelle in the rear for the widest wheel and tire combo. Trying to find out to set my car up on a set of rear 20's. I am thinking of purchasing a 66-67 rear 12bolt ( still need a axle) and thinking with this older body axle being about 5/8"s narrower might help me or am I on the wrong direction? I had a guy stat to me he was running a 11" wide wheel, you guys see it happening?

I am not looking at going as far of mini tubing.

Any thoughts or help with info would be great.
Thanks