That ratio was designed at the factory to provide full travel, both compression and extension, with a stock length shock.
It was also designed to utilize the spring rate for an average rider.
Changing up any of this will require a new spring at the least, possibly a different travel shock to make use of the new movement, and depending on where you bolt it on, might need either limiting straps and bumpstops or you won't get enough travel.
Personally, I'd leave it alone unless you knew exactly how the changes in leverage affects the shock and swingarm travel and you had a specific goal in mind.
Previous owner probably had an idea and it didn't turn out the way he thought it would...