This is my area of interest so I'm happy to chuck in a few suggestions. I know TW 1.3 has a limit of about 28mb before there are problems in a tour...does TW 3.00 have this?
If it doesn't then yes you can have much larger tours but I'd recommend that you think carefully about whether this is what you think your visitors might need? I add still images and voice-overs/sound effects to mine and this makes it a much bigger tour. If we say that someone will spend 30 seconds looking at a pano (which is what they do at the very least - usually it seems to be about a minute) then a 70 shot tour will keep them busy for over half an hour...if its 1 minute per pano then your tour takes an hour and do people really want to do that all in one long chunk? I'd have to say, based on my experience, I doubt that this will happen. What I would suggest is splitting your tour up into 10/20 pano tours.
What I've found, and you can disagree, is that it isn't the photo that necessarily makes the tour interesting...it is the information about why this scene is important.
Hope this helps and if you have any other questions then I'm more than happy to answer.