650 is about 250 more than I was expecting so that's decent if true. Always thought that Millwall's away support quite decent for the amount they get on at the Den, a bit like ours really, bottom 6 in the Championship in terms of home support but top half in terms of away support.
For all of Millwall's "reputation", the only time I can remember any bother in the past 25 years was in 2000 when we went 3-0 up in the first half and a group of 50 or so Millwall made an half-arsed attempt to get on the pitch and started throwing pies at the Town End. In the weeks beforehand it'd kicked off inside the ground at Wigan and Burnley, but that was par for the course it seems with Millwall in those days.
Should be fairly low key before and after the game tomorrow, probably a higher police presence than normal given the number of away fans, especially inside the ground, but away fans are welcome in most pubs in the city centre, even when a team brings 5,000+.