The simple answer is yes, if you could extend everything out, you could use massive offset wheels like newer cars.
The reality is it is already in practice, although not as extreme as some late model wheels. With a 15" wheel, about the maximum backspace you can fit on the front is 4.75. If you move up to a 17 or 18 wheel, you can now get 5-5.5 back space because the bigger wheel diameters clear the components that were in the way with a 15" wheel. This puts you in teh same realm of sizing as many late model vehicles.
However, with some careful component selction and a non-factory spec alignment, you can duplicate the late model feel and performance in your older car without all the hassle of relocating suspension points.
The back is a little different because the leafs are in the way. However, you can relocate the leafs inboard and do the same thing there. XV fits 335 tires in their cars when the leaf springs are replaced by the three link suspension, because the interference is gone. There also is the possibility of swapping rear ends to a wider version to achieve the same thing. On an E body, the only rear wider is a C body, but on something like an A body that is very narrow, you could put in a wider rear and use more offset in the wheels instead of narrowing the rear end.
So this is why you can see so many varied combinations of wheels and tires and suspensions that can fit inside the fenders of what appears to be very similar cars. There may be 5 different ways to fit similar sized tires in the wells without any two being exactly alike in execution.
