I went with 16x7 rims from XXR wheels (XXR 513 16x7). My tire guy (Action Tires) took the Z for a few days and tried on different tires until he found a nice 'fill' for the wheelwells. These are zero offset wheels.
He settled on a 205/55R16 91V.
I think the combo is respectful (enough) of the vintage (1971), keeps handling good and matches my Red/Black color scheme.
Sadly, the dust cap on the front wheel sticks out too far, preventing the use of the nice snap-in logo/cover/finishing cap. I painted the dust cap black and that's going to have to do for now.