28x10.5 15 slicks in a early dart

First off , I would recommend USCARTOOL for the parts to move your springs and mini tub your car . They have a package for the 63 thru 75 a body cars and are easy to install .
I would not spend money on a used set of tires .
The first thing to do is get some measurements from your car and write them down . Take a measurement from the inner wheel well lip to the frame rail . using this figure subtract 1 1/2 inches from it . This is 3/4 inches times 2 for tire clearance on the lip and frame rail . You can look on different tire web sites and see what they give you for tire size and side wall width based on rim width . It's just a bunch of math to do to come up with what will fit . Next you will have to worry about wheel back spacing and off set . This is just the tip of the issue . I have tubbed and mini tubbed 30 plus cars in the last 40 plus years . If you want to send me a PM and I will give you my phone number and I can talk you thru some of this . A few pic's of cars I have done .demon 001.jpg IMG_1720.JPG more 001.jpg