If you use modern style tires and sizes they would not be correct for a show setting and we would expect that if judged you will receive a measured and appropriate deduction for these non-factory choices.
A related discussion we recently had here on the site - http://www.concoursmustang.com/forum/index.php?topic=15486.0
Instead consider tires made by one of the reproducers, that is why they make them
such as Coker or Kellsey Hayes. They are available directly or through one of the resellers/dealershttp://www.kelseytire.com/home.htmlhttps://www.cokertire.com/
The challenge it that there is not one (as far as I can tell) perfect answer but instead closer to the goal, options. As mentioned in other treads, for black wall, the option of blacking out a white wall and installing the tires so that the non-covered side is to the inside of the car. Tire size is also a challenge but I think you need to make a list of what is available and compare those to what was originally installed and make the education decision from that point.
In a quick look I see
- Black wall Firestones in 7.50 x 14 so the height is a little off but most of the other details would work
- White wall or dual red striped Goodyear in 6.95 x 14 so good size but the stripes (might start with the red lines) would need addressing......
Hopefully other members will offer the choice they made with the same goal in mind.