I would contemplate if the work is necessary. If the kitchen is short then you might have an issue.
How much work and money do you plan to throw into this job?
There is a proper way and a shiming way.
The proper would be to sister the floor joists and create the proper rise you need to obtain level. This creates much work and litterally tearing up the floors.
you could Rent a Lazer level or water level and find out where the fall occurs and begin there with a 3/4 inch ply board cut at a sharp angle and make up the difference at that point and carry it on out. But with this increase, you have all sorts of issues with cabinets, door thresholds, and cabinets.
I really do not know about this working practically.
Other than marbles and round things rolling down hill, what about this bothers you?
You could also, if a pier and beam foundation, place some 4x6's under the kitchen floor joists and have them jacked up once a proper footing has been created.
Come back with more info and lets see what else can be done.