The fundamental issue with applying an inflation adjustment over long periods of time, is that societies are so different, that the typical basket of goods purchased is very different and less certain.

I like to hold something constant as a reference point, but you have to think about what, because for instance, if you're choosing between gold, silver, bread, beer, chicken, or beef, then you have to consider that they may have changed price dramatically relative to each other so which one you use makes a big difference.

I guess an inflation calculator is good if you really know what people bought, but it seems like information would be sparse enough that might mislead you. And like others have said, buying things with money, let alone documenting it, would have been far less prevalent.