1973 dart swinger rear tire

I'm interested on how your tires fit, contemplating between 27 and 26" Hoosier QTP at the moment. The trick is to get the biggest tire possible but it's such a fine line. Please let me know how the 27" fit cause I know I won't be going to 28 . I'm thinking I have to take some fender lip out and bang around inside the well for a bit for the 26 x 11.50-15. QTP .Section width is only 11" and the tire diameter is 26.4, think they will fit? With the offset kit and proper BS