??? This was already done through US Weights and Measures and the Coinage Act of 1792.
The Act established or defined the "dollar" as a weight of silver (371.25 grains (troy) of fine silver) and then regulated the value of gold coins to it in a 15 to1 ratio, that is, as 15 grains of silver to every grain of gold. The regulation also included establishing the purity and the various denominations.
Coinage Act of 1792: http://www.logoplex.com/shops/leaders/coinage1792.txt