Attack this wheel problem another way? You said mid 70s chevy truck...that would be 5" bolt circle 5 lugs if 2wd. If you could find an older Hollander Interchange manual, I'd bet you can find out which car brand/models used a 4.5" with that bolt pattern. maybe a base model late 40s/early 50s Studebaker, etc.
I did the same for older 16" wheels. I needed steelies to sort of match my 40 ford front wheels, but with an Olds 5 on 5" pattern. Hollander had quite a few models/makes that I could choose from. One wheel I found local, the 2nd one I just got on ebay.