68 barracuda tire size

The 14 inch Rally Wheels are 5.5s.That works out to about 140mm.using the 70% rule;
140/.70 =200mm= the optimum size of tire to fit on that rim. At 215 you are already past the optimum, by 7.5%.
A 235 needs a 6.5inch rim, which rounds to 7, cuz just try to find a 6.5 sbp,14incher.
To put a 235 on a 5.5 will tend to pull the outside edges of the tire up,off the pavement, unless you run a very low pressure. This is not a good idea. #1) at standard pressure,you will burn the center off the tire. #2) at reduced pressure, your car will handle like a barge in the corners.
I have run a 235/60-14 on a 7 inch rims at 29psi, on the front of my 68 FormulaS. The tires had a long life, and it handled reasonably well.
The rear can accept;
275s on 8 inchers,without mods.
295/50s on 10 inchers(24psi) without much trouble. Just careful fitment.
325/50-15s will also fit on 10 inchers, with the springs moved in 3/4 inch, and careful centering.