Lesseee. 275 lbs is 124738 grams. Gold is 19.3g/cc. So that's 6463.11 cc. Or 394.4 cubic inches of gold.
So, if the ingot is 9" by 9", that means it's 4.87" thick. Don't drop it on your foot!
Your calculation looks right. If you get the chance to handle gold in quantity the surprising thing is always how very heavy it is. You’ll never again believe a movie that has someone pick up a gold bar and run away with it.
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.