need help purchasing street radials for my 74 dart sport

Wow ! Thats a great looking Dart !
I like the look of the current wheels and tires but understand the desire to have a meaner stance . I have a second set of 255/60-15 M/Ts on 15x8s for both my cars. ( rears)
I do like the look of it and think the wheels match perfectly, but I wanna try out something with a little more grip and scarier stance. The 235’s on it don’t hold up to the amount of power the 360s making haha