If you need to change your config to use a Zmin endstop you'd need to make the following changes to the sections I quoted above:
homez
G91 ; relative positioning
G1 H1 Z-500 F6000 ; Move Z axis to endstop
G1 Z3 ; back off endstop
G1 H1 Z-500 F360 ; hit endstop again slowly
G1 Z3 ; back off endstop
config
; Endstops
M574 X1 Y1 Z1 S0 ; set active low and disabled endstops
You can leave the zprobe section as is, or add a ; to comment it out.