If you're contemplating lifting the forks 50mm get the bike on a steering head stand so the suspension will sag fully and measure 120mm + 50mm from all point of the front guard along the line of suspension travel to see that you won't be fowling radiators, fairings etc. under full compression.
As the bloke in the above thread says 2 inches is a lot.
Remember because the forks are angled at 25 degrees you will have to slide the forks up more than the amount you want to lower the bike. My back of the napkin calculation says you will have to slide the forks up 2.4" to lower the bike 2"