I think that will be fit, do you agree?

no, you still have the capacitor delay.

If you use a sample-and-hold, you reset it after the read, so you read, reset, read ... and thus get 200 or whatever IMMEDIATELY followed by 0 (if you cut the power at a null crossing). This way you get absolute readings.

Now for another thought.
I'm rectifing and filtering the AC and measuring the resulting DC voltage, when there is a power outage the capacitor starts discharging and messes my reading.
If you put a reasonable discharge resistor across the capacitor, can you not make a bit of code that say "If the voltage dropped from nominal to <? in n readings, change the last n readings to zero". This is a bit more code, but much simpler hardware.

Erik