It looks as though you are calculating in avoirdupois weights. Gold is measured in troy weight. 275 troy pounds is about 225 avoirdupois pounds, or just over 100 kilograms. The volume of the gold would be a bit more than 5 liters, or about 310 cubic inches, so a 9X9 ingot would be not quite 4” thick.
Pardon the imprecision, but I don’t have a calculator handy, so the numbers are in-the-head estimates.