There is far more to proper fit than just LOP - drop at heel, drop at comb, pitch,toe in or out, cast on or off, etc., all combine with proper LOP to make the gun fit and eliminate cheek slap.
A proper fitting can eliminate that when done by someone with a try gun. Unless you shoot as you tinker with the measurements, you might get it somewhat better, you might not.
Another factor in LOP is the angle of the grip - a more relaxed grip can allow you a longer LOP.
Do you shoot with a long or short pointing arm.
There are adjustable combs and recoil pads that can be installed and adjusted by the likes of Gracoil, GSquared, among many others if you choose to go that route. One advantage they have is that you can adjust LOP for summer vs. winter shooting - nice if you shoot year round with climate changes.