Actually, not even all the Computars and Graphic-Kowas are the same design. My 150mm Computar and Grahic-Kowa are both 6/4 designs. However, my 210mm Computar is a 6/4, but my 210mm Graphic-Kowa is a 6/6 design with less coverage.
Originally Posted by Dave Wooten
This change from the original 6/4 design to the later 6/6 construction seems to have taken place gradually and may not have affected all focal lengths in the series (for example, every 150mm Computar/APO Kyvytar/Graphic-Kowa I have seen is of 6/4 construction). This seesm to be the reason for vast differences concerning the reported usable coverage of these lenses. They all look pretty much the same, but some cover less than others.
Not sure on the 300mm Konica GRII, but the 210mm is reported to be a 6/6 design. So yes, it is likely the same design and offers similar coverage to some Computars and Graphic-Kowas, the question is, which ones?