low leakage caps

The original question was because the old caps were low leakage types, and he didn't know what to do.
He also thought that polarized capacitors were necessary, to function properly in the circuit.

Modern quality parts will be far better than the 'low leakage' parts of yesteryear.

Looking at the circuit impedances and DC voltages around that stage I still think it is a non issue and would be happy fitting what I originally suggested.

If the originals have deteriorated and are down to only 0.25uF then the replacements will make a big difference.
 
Modern quality parts will be far better than the 'low leakage' parts of yesteryear.

Looking at the circuit impedances and DC voltages around that stage I still think it is a non issue and would be happy fitting what I originally suggested.

If the originals have deteriorated and are down to only 0.25uF then the replacements will make a big difference.

Yeah, as long as the electrolytic isn't a solid polymer cap it will probably lower leakage than the old cap.