You can run a ps rack dry no problems, but as said would need to remove the pump.
The rack would seem a lot heavier due to obviously no ps, and the rack most likely being a bit higher ratio, less turns lock to lock, if you took the rack apart and removed the centre seal on the rack itself it would make it a bit lighter.
I built up a 2.2 turns lock to lock manual rack for roosie for his 3 door track car, that's as high as you can normally get.
tabetha