I am in the process of sizing up new wheels myself, and this thread is serendipitous.
With my disc conversion, I need to upgrade from the stock 14 inch wheels to some 15 inches at least, though I am considering going to 16 inch wheels.
Trouble is, my car as I bought it doesn't have the wheels--they were 'misplaced'--so I have no idea what the stock offset would be.
Fossil Fuel (or anyone who can answer)--The example the OP gave was an 8 inch wheel, and you commented that it would work. If it's an 8-inch wheel, with a 4.5 inch backspace, does that mean the wheel has 0.5 inch positive offset?
I'm looking at going with a set of Cragar Steel Wheels (around $60 bucks from Summit--cheap, I know) but I can't find a local supplier that seems to realize they are cheap (they all want $150 + for the exact same wheel), but with shipping charges I want to make sure I get the offset correct!