67-69 barracuda front tire width

Most of us just reach into the toolbox and haul out the tin-snips.
You need a good inch clearance from the fender corner to the nearest part of the tire as it travels thru it's arc, and travel. And the reason is because when you are backing up and turning, while riding the brake, the tire is gonna get into the fender real quick, as the strut rod moves ahead. A half inch at ride height, is not enough.
If you run much taller than the E70-14s,and push them out further than the factory IIRC Zero offset wheels, then you will start to get into scrub-radius issues. This is manifested by the car following every longitudinal ripple in the asphalt, no matter how you set the alignment. So there you are with a constant nervous twitch that never goes away; It's a royal PITA. On concrete it's better but still nervous.
My 235s mathout to about 25.1 and are reasonably well behaved with a 3.75bs. I run them at 29psi for long treadlife; the rim needs to be a lil wider but 14x8s on 4.5bs occupy the same space as the Upper BJ, so that's a no go. 15s with a 4.5 bs will clear the factory small BJ, at ride height, withe wheels pointing straight ahead; and if you never turned more than a few degrees, and never cycled the suspension very far,it would be fine, lol. But IDK about the 73 knuckles and later BJ.
You need a 17 to get up and over the BJ. And then the tire gets into the strut rod. and the frame.

I don't know if you are aware of this, but a radial passenger tire is only the branded size on a rim that is 70% of the branded size.
So if you have a 215, the 70%rim would be 150, rounds to 6". This is not the recommended rim size; just the size used to create the branded number, Furthermore the brand is rounded to the nearest 5mm. So a 215 could be as little as say 210.1 to as much as 219.9; both round to 215. This is important to know when calculating heights.
If you put that 215 on a 7" rim, the section might grow .5 or a tad more. So then your 215 becomes a 227 +/- 4.9mm. which is 222.1 to 231.9; that's a range of nearly 10 mm. By itself this is not important, until the sidewalls rub on something, because your calcs are skewed. Like when the fender comes down on the rear tire when you hit a pothole.
I finally narrowed my rear and relocated the springs. Now I can run any common 4.5bs wheel, up to 10 inches, even at my lowered ride height.
Don't forget about the stepped lip in the rear tubs. If your rear sits low, the wrong offset rim can put the tire into that lip pretty quick. About the tallest tires I have put into my Barracuda rear, is 28", but I had to push the axle back a bit. 27s fit fine.