I’m about the same weight as the op, I had a lyrik coil 170 dh running the medium spring. I ran mine with about two clicks of low speed compression and no high speed.
I’ve changed to a totem coil, medium spring and I run pretty much the same settings. I use full travel or 95% maybe once a run on a dh track and wouldn’t be concerned if I didn’t.
Slow Speed compression is for just that slow speed hits when the fork is moving slow + on the slow gives more resistance on slow speed travel.
I don’t really agree with that explanation – I think of lsc as rider/gravity input, ie if you are riding down something steep or flying round a big berm more lsc will mean the fork will sit higher in it’s travel.