4k7 uF is aceptable, so is 10k uF. I ran a bit on the iffy side with 10k uF @ 16 V. I hope yo guys can see the risk in that. L-C filter with ~18 vac will over-voltage them in a big way if no load is applied to the filter.10k was just as easy for me to get as 4k7. You'll be fine w/either. I keep forgetting to limit your options, and act like a dictator.
Gilligan, dreaming, promises the crowd, "this, that, and the other thing..."
regards,
Douglas