I think the best thing would be to rotate the songs a bit. Say, at one gig play Children Of The Damned and Powerslave, then at the next gig play Revelations and Stranger In A Strange Land.
That'd be the best thing to do, since they'd dig out a lot of oldies. Then they could maybe put these tracks onto an album and release it, so it's just the songs unplayed for years, and it doesn't have the staple songs we've already got. A bit like side 4 of LAD.
It's probably not going to happen, but I can wish!