Upload the pic...I have no idea what exactly you're talking about.

For your viewing pleasureee

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...

Before you change anything, check travel limits how it is so you can see what kind of difference it makes.
Then put it back where it belongs and adjust spring preload if necessary.
It might not make much difference, might surprise you, who knows?
OEM setup has been working just fine for pretty much everyone who owns a 250...so it's a pretty safe bet.