Replacement electrolytic capacitors may be found in the primary of a switching power supply (try disassembling an old PC supply for parts) -- they're usually rated for 600V and of fairly high capacitance.
wax/Paper and mica caps can be replaced with ceramics.

The vibrator is a device from hell -- you'll not find a replacement unless you're extremely fortunate. Their function in modern equipment has been replaced by a pair of transistors...

If I were rehabbing this flash, I think I would opt to replace the voltage converter with a switching supply. Just treat it as a "circuit block" and put a modern version in -- far less trouble in the long run and you would end up with loads of extra space as a bonus!