RVR 300' ( 91 m ) wow that's way below CAT3B territory and I think you'd be
told "RVR 300 feet". Couldn't even takeoff with 300' RVR
Think you may be a bit confused there
Nitpicker, CAT3B can be zero/zero in terms of viz and cloud base for both landing and take off, depends on the capability of the aircraft/state of airport aids/crew recency etc. as well as your own airlines SOPs. Been a while since I did one but I seem to remember 75meters and 20' as the landing minima for the B747-400 that I flew and that had more to do with taxying than landing.