You might be thinking of [natural units](https://en.wikipedia.org/wiki/Natural_units). If you based your system on G and c, where G is the gravitational constant and c is the speed of light, to convert time to distance, you multiply by c; to convert energy to distance, you multiply by (G/c^4).
It's more usual to do the reverse; that is, to express everything in terms of energy rather than distance. This is why particle physicists express almost everything in terms of the [electron volt](https://en.wikipedia.org/wiki/Electronvolt), which is really a unit of energy.