To put the relationships into perspective, if it is of any interest:
For a typical ILS PAPI, you'll have three whites 0.25 deg above the nominal.
For a three degree PAPI glide path, you will have 3W/2R ten feet above the three degree GP when the GP height is at 120 feet.
Proportionality gives that when the PAPI GP is at 60 feet, it takes 5 feet above to get three white, and at 240 feet it takes 20 feet above.
Cheers,
/Fred