[techiesteve]

Personally I would never try to achieve matching a 0.05uF capacitor with 4 in series parallel, but simply use a 0.047uF of adequate voltage. Not as common as they used to be, but can still be found.

Re electrolyics in series, I would always use adequate balancing resistors. What is often overlooked is the voltage rating of a resistor, this can vary and may be unknown if using a junk box part. I worked repairing SM PSU's for many years, and a common failure was the inverter transistor, sometimes FET, failing, due to one of the series connected reservoir caps. One of the 2 balancing resistors will have failed and the cap sometimes had the top vents bulging and was low or open. Two 200V capacitors in series with 330 - 340V across doesn't leave much margin.