255/60/15 - stock 70-72 Dart

OK, I'm looking for a definitive answer here. Went through a lot of old threads but could not find the exact answer I need. Sorry if this seems repetitive.

I am trying to plan out a wheel/tire combo for my '71 Dart. I am hoping to fit a 255/60/15 M/T Drag Radial in the stock wheel well with the springs in the stock location on my 8 3/4. A 235/60/15 should fit no problem since I have 245/60/14 on there right now with plenty of room. There do not seem to be 245/60/15 available in this particular tire. Yes, I can get the offset spring hangers but naturally this = more money since I'd need to buy the parts and don't have a welder. Not a big deal but I'd like to avoid it if possible.

So again -

1) 255/60/15 M/T Drag Radial in the stock wheel well with the springs in the stock location with no issues (rubbing etc.) - yes or no?

2) if yes, what is your backspace and what rim size are you using?

I don't have a floor jack at the moment so it's kinda difficult for me to measure things.

Thanks!