We are currently doing a 5-year span with 4 teams per division, and that's hardly an All-Star roster I've got out there. So a 5-year span with 6 teams will definitely raise the challenge. I'm game for whatever, since it forces you to use lots of less-used players. I'm less familiar with the early 70s than the late 70s (since I was born in 1970, I was a little young still), but challenges are good and the research is always fun.