The only real solution I could imagine would be to look up estimates of purchasing power parity throughout time.

There are several issues that complicate answering this question.

• Economic systems have varied throughout time

  For example, how would one compare contemporary wealth to a person living in a barter society? Is being allowed to use debt or make investments a factor, if so how would one measure inidividuals living in eras or locations that did not have these concepts?

• Classes and their power vary between societies

  "An elite" is very broad. There have been many members of nobility who were far from wealthy, hence the existence of power struggles and complicated marriages - and "dominant power" is troublesome as well, can we distinguish a baseline of wealth between an Ottoman sultan, a Japanese shogun, an English duke, and a Roman senator? And who is an average poor American? I can live off $18,000/year in a small midwestern farm town, but would find it much more difficult to do the same in Seattle.

• Commodities fluctuate in worth and some goods are of subjective value

  Owning a horse today is generally a luxury expense. What would be considered craft beer today, was at one point the only beer available. On the other end, a cabinet full of cinnamon, cane sugar, basil, sage, tumeric, and cloves today is nothing too fancy. In a historical context, geography also plays a role in commodity worth, a medieval Chinese bureaucrat would have silk clothing that would be worth way more to a European than to himself. What about access to education? Certainly an impoverished American doesn't have easy access to school, but with state programs and scholarships, the very idea that a commoner has access to education could seem like a benefit to the modern poor, but really, tertiary education is becoming less of a luxury and more of a necessity, as more places look for degrees for entry level work as divisions of labor become more expressed in a developed society. How do you measure/compare that? Is it about access to education in a vacuum, or about being able to secure a vocation?

• and of all three of these issues, none occur contemporaneously around the world.

For purposes of discussion the US Census Bureau considers a single person with no children under the age of 65 to be under the poverty line if they make less than $12,119/year.

I can't help you on the topic of PPP, because I don't fully grasp the concept with enough competency to relate/apply it to such a thought experiment, but for general purposes, two units of money are said to be on parity if x (unit a) can buy x (unit b), and x (either unit) can purchase equivalent goods or services, for example a big mac. For the purposes of this experiment, you'd need to agree on a single commodity unit, and find historical figures for whom massed wealth has been estimated, and then last find a reliable source on historical PPP.