K folks, it's been a tough end of the school year unlike any other, so I'm finally able to return to the project.
Rear tires are slightly larger than the front ones, and going into my spare tires resulted in only mismatching tires of differing sizes. Fortunately I was able to source tires of the same type/appearance and apparently correct sizes from Fireball Modelworks. Fortunately they also fit the wheel rims that a fellow modeler was kind enough to send me.
Then the inner wheel hubs had to be reduced in size to fit the tires; had to do this now so as to know exactly how far to raise the rear suspnsion.
To make the extensions, I needed something thin yet strong....so just making them out of plastic strip wouldn't do it. They might look the part but they wouldn't support the car past one sneeze. Fortunately I keep unused Photoetched fret, and the slightly thicker part of the metal sprue just might be strong enough, especially if doubled up.
The main load will be supported by an inverted, angled "U" shape. The height was kept accurate with plastic plugs. Then the more visible parts of the brackets will be attached to the outside with more metal fret.