The condenser "set" should match the lens. Theoretically, a 6 x 6 set should perform best with an 80mm lens- "standard" for 6 x 6, or a wide-angle lens (60mm or ?) designed for 6 x6 coverage. I don't think there is a great deal of distinction between 6 x 6 and 6 x 7, however.
Wildly mismatched sets, 35mm used for a 4" x 5" format, for example, can be expected to give unven illumination with a lot of edge fall-off; or, going the other way, reduced overall illumination.