What fietbobs said; look at pics of racing bikes in the 40s and so on. Theories have changed. Top tube length is, IMO, more important since it dictates your center of gravity. There comes a time when the seatpost is too large but as long as you clear it (and the OP's pic shows that he or she does), then you're good. I'd be more concerned about the relatively short stem (assuming that the stem length is correct).