Assuming, just assuming that those dimensions given were very very accurate, the computed SG is 18.09. Gold bars in WW2 have SG from 18 to 18.78. However, the weight of bars in WW2 are 6.20 to 6.30 kgs and exactly 74.6 kgs.

I ain't saying that those were fake or genuine since no one can accurately say such by merely looking at its picture. Have it assayed before the deal.