However, if you had a 20 gold coin from the 1800s, both then and now, that amount of gold would buy you a really nice suit.
Then and now, most likely.
Gold price is heavily influenced by speculation and the buying power is far from fixed.
About 20 years ago, that ounce of gold dropped to nearly $300 USD.
About 40 years ago it was over $2000 and $300 gold in 20 years was unimaginable.