ZXR 400 rear ride height

Hi all,
On a recent outing at the track on my ’91 ZXR 400, I got my crap together and really honed down my lap times. I really surprised myself and I’m very happy! Although I found that I was scrapping my toes and foot pegs excessively. So I’m looking for some rear ride height increase. I have what looks like a height adjuster on the top of the shock, with a nut above and below the upper shock mount. I’m looking to adjust that to see how much more height it will give me then adjust the preload nuts on the shock itself for sag...... Is this the avenue I should be heading up? I’m aware that the changes to the rear height will change the handling up front also so I’ll cross that bridge when I get there. The hope is that with 2-3 cm height increase at the rear will also relieve the cramped effect I currently have with my legs and the angle my knees bend at when sitting on the bike. Currently when I sit on the bike I am flat foot to the ground with a slight bend to my knee so it is pretty low!
How much height increase/ decrease can be achieved with this height adjuster?
Any input would be much appreciated!

Do you have a stock peg set up?
If not rearsets would give you more clearance but you would be more cramped so its not really a solution.
The ZXR400 steers pretty quick bog stock ...... raising the rear end might make it handle pretty bad, as you would need to max out with the ride height by the sounds of it.
Have a look here as there is a plethora of info...... one of my favorite sites, its a beauty!
http://www.zxrworld.co.uk/zxr400/main.htm