Hi there Dean. Im not an expert but know a bit. First I would ensure the forks are in face serviceable. Check there is fork oil in there, correct weight and the correct level. Fork seals in good nick and not leaking. Im thinking when you raise the rear you will put a little more forward weight on the springs, like pointing the bike down hill a bit. It will load it up a bit and may make it twitchy at speed. Will feel lighter. You may get a wobble at higher speeds, not good. Heavier, stronger springs will be stiffer and not bottom out as easily but you can go too far. The weight of the fork oil controls how fast it changes position. So thinner is faster. Try doing some searches on suspension on the u-tube there is some crap but other posts are on the money.
Currently looking at sag, race sag for the rear shock for my DR650. Mar need a stronger rear spring. So learning heaps.
Check this out to set up the rear.