The secret is that you just need a range of numbers to use and lots of obstacles to roll against.
A lot of OSR games tend to have numbers from 3-4 (damage, weak creature HP), 12-15 (AC/DC), and only a few numbers higher than 20 (boss HP, etc). A single dungeon room might have 4 goblins (each with 6 HP), 3 piles of treasure, a fire trap (DC 14), and a dragon (d12+4 damage). All in one area.
But Blades in the dark (and other story games) have scenes that flow from one to another. I don't think Overpowered would be as satisfying to play through unless you laid them out in greater detail (6 guards around the manor, 3 ghosts in the vault, etc etc).
For shadowrun I would use the pool sizes. E.g. if something has a soak of 12 dice, then you need to spend 13 or more Power to overcome them.
If all else fails, then simply assign your own values to things.
Minor obstacle - 4
Average obstacle - 8
Tough obstacle - 12
Major obstacle - 16
I hope that helps!