1968 Dart 2.8L Tires

215mm wide, but the 70 is a ratio between the sidewall and tread width. 215 70r14will be .6 taller or .3wider from the spindle to the edge of fender lip than a 205
Stock tire was like a
Standard tire size:

6.50 - 13

Tire width (mm):

165

Tire sidewall factor:

80

Rim size (in):

13

Total wheel diameter (mm / in):

594 / 23.4
and the 205/70r14 is 25.3 tall. It will register slower on the speedo (60 register as 55) as it turns slower to cover the same ground, and will act like a very slightly shorter gear in the back ie. Slower acceleration but faster top end.