zeffy
I think that most runways fall in the acceptable catagory of slope and that there is not a correction for actual performance (at least runways that most airline would use) certainly corporate planes are much more flexible in their destinations.
check your limitations section in your manual and you will find something of interest. I checked the nearest manual I had, a bae 146 and there is a limit to runway slope +- 2%
in this way you are covered...but again, my discourse is on the prolonged float and visual illusion part of the slope.
smack it down on the 1000' marker, hit the brakes and thrust reversers and you should stop (ice...well)
but indulge in a prolonged float due to visual illusion, and you might not stop on the runway (think air france yyz)