Playing "Spartacus" - it has become a little folk song, by the way, since IMO rock music would not fit - I found that it was way too short. I used to repeat the last verse, for which I had altered the chords a bit so as to make it a little more dramatic:
tied to their crosses
soiled, and half-decayed
there will remain the message
that they have conveyed
Today I came up with the idea to repeat the first verse as well at the end of the song, with a slightly changed text:
we will break through your lines
and teach your armies fear
when you'll think us besieged
we'll attack you from the rear
Now I think the song has got the timeless quality which I was striving for and it has fallen into shape. I will record it sometime soon, and you will find it on my other pages in case you're interested.