Duffman,
Does your Marti report call out chrome style steel wheels? If not, it would have come from the factory with the argent painted styled steel wheel with reflective paint. The chrome steel wheels were a separate option in 1968 and would appear on your Marti report. 3M used to make a reflective paint, it has long been discontinued. Highway Departments and sign shops used the reflective paint. You may be able to paint the wheels with standard argent paint and while still wet sprinkle glass beads into the paint. the glass beads will reflect the light. I've never tried it, but a thought...or you can try the reflective clear coat you have already used.
I hope this helps.
Danny