once you upgrade bowden setup to DD one and replace plastic extruder mount for an aluminium one - there is lack of mounting point for a filament sensor. Since I use Sunlu S2 dryer placed on top of the enclosure it is handy to have the sensor at the top as well.
Filament in/out holes are 4mm in dia. so you can screw PC4M5 or bowden tube directly - up to you.
V-slot mounting screw - M4 with T-nut.
Two M3 16mm screws and nuts (not required as the sensor sits very tight.