Removing the leveling kit would be the best option, how difficult it is depends on how it was installed....if it's a bolt on it should be easy to remove. However if they replaced OEM parts with new/different kit parts, then you will be looking at parts costs in addition to labor costs to remove.
Maybe snap a few pics of the front suspension and post on one of the Toyota forums and see if anyone can identify the kit and tell you what's involved in removing it. There's likely only a couple of kit options for your specific truck, so somebody should recognize it, not like there's a hundred choices....
This
Rough Country Kit says it's easily removable and easy to return the vehicle to its stock height.
Here's an assortment of kits at
Summit Racing, see if you can see one that looks familiar.
