I honestly don't know, but I would bet large....not.
I have a pair of 235/75s for my 62 Savoy, and it has a huge wheelwell, and it still needed the front edge "relieved" for clearance.
From what I understand reading here, a 26"tall tire is pushing it on the front of a Dart.
And just about any tall tire on my car rubs a header tube at full lock. (2"tube, one trough the wheelwell on each side).
