largest rear tire on stock wheelwell 69 dart

BBP or SBP, and what rear axle? Stock spring locations?

The "standard" offset on the 14x7" Cragars is probably going to be your limiting factor. A lot of those cragars have a negative offset, most are zero offset at best. And either of those situations will keep you from running the widest tire possible even with SBP rims and the stock spring locations. To be certain we'd need to know the backspace on those Cragars.
sbp, 8 3/4" rear end with 3.23 gears stock spring location. don't know the offset of the wheels I can get that checked tomorrow. thanks for so fast a response and your help. brian