I just used the standard equation I have been using for most of my life for converting capacitance in an AC circuit into a resistance equivalent at a fixed frequency.
I have built many power supplies that way. Here is a site I use for doing the calculations fast and easy.
Free Online Calculators for Engineers - Electrical, Mechanical, Electronics, Chemical,Construction, Optical, Medical, Physics, etc... I just used the resistance-frequency-capacitance calculator to get my estimated values.
I reasoned it out like this, given a line voltage of 220 volts and 60 Hz and a peak output of 30 volts I would need a resistance equal to 63.33 ohms at 60 Hz. From the calculator I get 42 uf as a value. If it is a 50 Hz system then I get a value closer to 50.3 uf.
I added 5% more capacitance to my earlier recommendations for overhead purposes on the 3 amps part to help with peak power capacity and to compensate for forward drops and the misc power losses associated with these type of circuits when used in real world working conditions.
As far as harmonics go the OP never said anything about them anyway he just wanted down and dirty basic design with no IC's.