I like the wheels but I don't think the go well with the color of my GS. Good thing or I would be tempted.
The originals in that photo are 225-70-14 but I photoshopped scaled the Hurst wheels to fit in the photo. I think those wheels would look good on a darker color car.
I would say for an 8" wheel, you'll want 5 or even 5.25". For a 7" wheel in the front, 4.5" should do. Maybe some 67 guys could confirm. I know on cars earlier than 70, you need more back space comparatively. 4" isn't going to cut it. Have a look at this thread, http://www.v8buick.com/index.php?threads/4-75-bs-17x8-on-67-gs400.331418/#post-2781929