I ended up buying the wheelwell lip rolling tool from Eastwood for my ‘69 GTX, and it gave me an extra 1/2” of tire clearance.

On my car I have the 295/65/R15 BF Goodrich Drag Radials on 15 x 9 w/4.5” Back spacing, and will change the tires to 10 x 11.5 Quick Time Pro Cheater slicks with tubes. I have the same setup on my ‘68 Super Bee, and I have more room as far as width, and could have gone with 10” wheels.

Your car is different, but you may have more room between the spring and sidewall, so maybe a little more back space?

Mark