The large caps are spec'd as 33,000uF. The output of the power supply is 40.5V, so the caps are almost certainly rated at 63V, do not go lower. I would suggest Mouser or Digikey for caps like these, look for 105* C rating, low ESR/high ripple current and of course they will need to physically fit in the straps. Other sizes could be accommodated but you may have to buy or make a suitable strap. Be very aware of the polarity, they are not the same, one side is the positive rail and the other is negative. If you have an ESR meter, you could measure the caps and compare that to what new ones are spec'd at, they are likely OK but all electrolytic caps will eventually dry out.
There are bleeder resistors in circuit, it should be safe after few minutes but measure and be sure!