Place a 1M 0.5W resistor across the capacitor to discharge it, and you can safely make it a 0.22uF 250VAC class X or class X1 component, a lower current through the opto will still work. If you do not want to use a leaded resistor use 4 220k 0408 SMD resistor in series to replace it, you have to use at least 4 to get the voltage across each resistor low enough.
Make the 220r resistor 1k or so, it will reduce the surge current through the LED a little with spikes. Make sure it is a 1W resistor. Add a 275V MOV across the input as well for spike clipping, along with a 1A mains rated fuse.
Other than that it is a simple circuit, it does need attention to clearance distance between mains side and the output side, and for the bridge diodes you can use almost any diode, from a 1n4148 to a 1n4007, it only is handling 20ma and under 5V in most cases. You can also add a zener diode of anything from 10-30V in parallel with the LED to provide a current path if the opto goes open circuit. If you add it in series it makes the zero crossing pulses a little wider so that the output side can more reliably trigger from them. There will be a phase shift from the capacitor, so do not use this to drive any phase switch other than a zero cross switching one.