You can substitute C5 in the Cataclysm with something higher, 22uF - 100uF.
For the Viceroy, you could double up two 4.7uFs in parallel to get 9.4uF, or two 22uF in series to get 11uF, both would be close enough.
They don't really have to be 25V unless you're going to power it at 18V.