Capacitors for Sony SS7300A

They should be fine for the three (3) values you mentioned, the newer capacitors should also improve the SQ. Going to 50µf as apposed to 47µf will cause the crossover frequency to be REDUCED by about 6%. For 70µf it will lower the crossover frequency by about 3%. And for 6µf, the crossover frequency will be reduced by about 3%. I did not do an actual calculation for a 2nd order crossover because I didn't want to spend the time and do more research on the actual slopes in the speakers, so these are rough estimates. I did not take into account the other components, as I'm assuming you are not changing them and don't have a schematic of the crossover. Considering the tolerances for older capacitors is at least +/-5% or more, I'm confident that it will be okay as I mentioned at the beginning. If some other Augiogoners want to spend more time, they could give you a more accurate assessment, good luck. 

Many Thanks Fiesta,

I shall have a go. I would have attached a circuit diagram but this model is a one off with a very different circuit from the standard SS 7300.  I salvaged them off the street and replaced the surrounds because they have neodymium magnets sandwiched between copper plates, to stabilize flux and give a linear response. High quality components. Well thought of in 1972.

Cheers   Rusiate