Josh, 1st very few report getting the 3" advertised but don’t worry about it. It will give max lift without binding the stock CVs.
I’m surprised you still had 10.25” with the stock 08 springs. Perhaps it wasn’t settled!
I installed the HL springs before the 3” Roktek and saw worthwhile gains from both. Crank the preload as needed for now. But you won’t regret adding new springs to the equation. I don’t think you’ll want the spring spacers in there with the new springs. I’ve only had one friend/passenger that I usually run any preload added.

 

the only way to get 3 inchs out of the kit front and rear is with spring spacers in front and all 4 shocks put on highest preload.

i speak from experiance.

 

preloads adjust ride height to counter for added weight. when you turned them back down you took that ride height away because your rzr didnt get any lighter. any lift kit you put on a rzr that doesnt bind the cvs at full droop is essentially the same as turning up your preloads. all you've done is taken 2 steps forward and one step back. turn those preloads back where they were and you'll get the lift. if it rides too stiff its something you're just going to have to deal with. changing springs wont help that. if you go to a softer spring such as a progressive spring is during the first inch or so of travel, you'll not have as much lift. its give and take unless you want to go wider.