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2 inches sounds like a lot.
There are bolts that compress the triple tree to the front forks.
I do not know if you could adjust them for a two inch difference in back.
You would adjust them to where you would be comfortable in the handling of the bike from in all its aspects from leaning into and out of a turn, breaking while in a turn, Breaking in a straight line, how much faster or slower is the handling, and anything else you can think of.
Your personal comfort is really important with the bike.
The safety in handling is more important first though.
I do not know of a formula as that would entail drivers weight and stance also into it.
You would need to trial and error.
Before loosening bolts on triple tree, make sure the bike is supported in the front with something you can raise or lower as needed.
If the front is not already supported when loosening, the tops of the forks can slam the bars above them.
Sometimes the forks stick and need to be bumped with a rubber mallet.
Another possibility without much cost would be a different, smaller rim.
The same handling rules would apply as it should change with a smaller rim.
For more money and more wrenching experience you could change the entire front end and install a different swingarm in back.
Possibility that you could find shorter forks that are the same diam as the OEM parts only shorter and with more modern internals, brakes and rims.
Many on this forum have done similar with the bigger bikes and I have seen a few on the 550 also, usually the E versions though.
No matter what you decide make sure the bike handles well first.