To me, your fingering makes a lot of sense; if you have to play an arpeggiated chord consisting of four notes, it would make sense to use four different fingers, so you can repeat your fingering each time the chord repeats. Now we only need to decide which four fingers (and in which order, although that should be obvious from which fingers you want to use).
If you want to arpeggiate a chord over multiple octaves, you need to move your thumb over; because of this, it would be a bad idea to use the fifth finger on the last note of the chord, since it's really hard to do a thumb-over after a fifth finger. It can be done, but if you have the choice (which you seem to have) it is just much easier to use another finger on the last note before the thumb-over. So, use the fourth finger on the last note. Since we need four fingers, we can derive that we need to use all fingers except the fifth: C = 1, E = 2, G = 3, B flat = 4. You can even recycle those fingerings for most seventh chords, except where you have a black key as the first note, on which you should avoid if possible to use your thumb.