Tire selection???

Stock spring locations?

You’ll only have about 11” from quarter lip to the springs. Sounds like race only for this set but you still need enough room for the sidewall to flex so even if you space it perfect your section width is gonna have to be no more than 10.5”. For the street or anything not in a straight line more like 10” -10.25”.

If there’s no tub work I don’t know that I’d go much taller than 28” on a Dart unless you want to play around with the wheelbase to fine tune your tire clearance to the front and rear corners of the wheel openings.

Not sure how wide your S60 is but a wheel mounting surface to spring measurement would go a long way to figure out if the 4.5” backspace will work.