If you have an A/C downgrade inside the OM and don't have your required RVR (as you quite rightly state 50'/200m for Land 2) you must go around (unless you have an emergency, then you can argue all bets are off).
If you were land 2 when you started the approach (with 200m), then inside the OM the weather reduces to 75m you can continue to your decision height and see if you have the required visual reference (3 lights).