Great article. Just ignore the pendants.
However, one cubic inch of gold weighs 10.1788 oz Troy, not one ounce.
Gold in 1947 was about $38 oz Troy.
The optimum packing fraction for coins is about .9 (90% of a space will be occupied by coins, the remaining 10% by air, there's no way around it) so you have to multiply the volume of the hill by .9 to find the volume occupied by coins.