3 degree glide path:
V/S = Gnd Spd divide by 0.2 + 50. e.g. 170/0.2 = 850 + 50 = 900. If the G.Spd is 175 round up or down to 170 or 180.
If slope is slightly steeper add 50 or 100fpm and see what happens. Reverse is true for shallower slope.
Nor sure what would happen on 6 degree slopes into special runways.
For those that say look at the Jeppe plate; I say on a dark night the text is too small to read. On modern EFIS a/c you have actual G.Spd readout, not an estimate from tower wind, so why not use it.