It surprises me that noone's mentioned Forge of Foes, that has a CR to level comparion chart.
But Giffyglyph of Reddit has made 4e-fication of 5e monsters years ago. You could do worse than checking it out:
Disagree. There's a big difference in how the North is presented between 1e and 2e. In general, the North is a much more dangerous place in 1e. Here's an old rpg.net thread about the changes in the North between 1e and 2e.
It was both. I can't find the answer, only the words divided among the cell blocs. Since I'm apparently blind, what is the solution and where can it be found?